All right, I've been trying to compose this answer for quite some time now. I'm not sure if it's going to come out the way I intend, but here goes! (Note: this answer is in part a response to the original question, and in part a response to other answers' suggestion that we change our scope to be about "everyday English." So if there is any confusion, you might first read other answers.)

##Why is (and should) ELL be aimed at non-native speakers?##

The simplest answer to the OP's question is **"ELL has *non-native speakers* in the byline because that was the purpose of creating the site."** ELL was originally created to answer questions non-native speakers encounter while learning English as a second language. 

ELL exists for the purpose of helping non-native speakers learn English. **We would not have a site today at all if ELL hadn't begun with this goal in mind.** It's the unique perspective that a non-native speaker has when learning a new language that has built the foundation of intriguing questions and answers we've collected so far. We should be embracing this perspective, and continuing to tailor our answers to it, not dismissing it.

We're about answering **questions that come from a non-native point of view.** These questions **are not by nature "easy" or "everyday".** They're just from another perspective, and the answers are as well. ELL is not about "questions any native speaker could answer" or "basic questions" or "questions about common everday English." 

 * If the questions were easily answerable by any native speaker, we wouldn't have *expert answerers*, which is half the foundation of any SE site (the other half is curious askers; the non-native speakers that make our site possible). 
         
 * The questions are not about *everyday English* because **non-native speakers aren't just looking to learn everyday English.** Some people learn a foreign language to communicate socially or at work. Others so they can read, or write, or watch movies in a foreign language. If a non-native speaker wants to learn English so they can read books written in old-fashioned (non-everyday) English, who are we to say that isn't a valid reason to learn (and refuse to answer their questions)? (There is of course a fine line between and English question and Lit-Crit, but the distinction between native and non-native speakers is irrelevant there.) 

I think that the unique perspective of non-native speakers' questions (and tailoring answers to this perspective) is what makes answering on ELL so interesting. Not only would eliminating this make discerning an "expert" pool of answerers difficult, but I think it would cause disinterest among some of our current top answerers. (I don't claim to be a *top* answerer, but I know I would lose interest.)

##This is a major scope change##

Changing the focus of ELL from being a site **for people who are learning or teaching English as a foreign language** to a site **for questions about everyday English** is a *huge* scope change. Really, really big. And I just can't come up with a rationale to justify it. Perhaps I could see a reason for the change if ELL were really struggling—if all our stats were down, we weren't getting many questions and the ones we were getting weren't getting answered, and everyone was losing interest—if we really thought the site was failing, the writing was on the wall, and we had to do *something* to stay open, then maybe I could see making a scope change as big as this one. 

But that's not where we're at. We're doing pretty great. Are we ready to graduate? No, not yet. That takes time. But we're chugging along at a respectable pace, and [hashing things out on meta to get us there](http://meta.ell.stackexchange.com/questions/800/how-can-we-encourage-current-ell-users-to-be-more-active). And honestly, if we *were* in dire straits, I'm not sure I could advocate for this scope change even then. If our basic scope were so flawed as to be unsustainable, I'd say "Okay... Let's head on over to area51 and try again, then." **This scope change is so large that it seems like a fundamentally different proposal to me.** It's like if instead of creating Programmers, Stack Overflow had *turned itself into* Programmers (and Stack Overflow had disappeared.) It just doesn't make sense to me.


##We need to focus on ourselves, not ELU##

The most recurring arguments I've heard in favor of this scope change involve ELU in some way. The two big ones are "Look at all these questions on ELU that could fit here!" and "But people are still getting confused about whether they should post their question on ELL or ELU, and that needs to stop." There's far too much emphasis here on defining ELL's scope based on ELU's. 

Obviously we have to coexist with ELU; since we have some areas of overlapping subject matter, we can't pretend they don't exist. But ELL needs to be able to exist viably on its own in a bubble universe... **If ELU disappeared tomorrow, we'd still have to be able to reasonably justify all our policies without its existence.** Obviously two sites that do exactly the same thing is bad, but *we don't* do the same thing. We are focused on answering the questions of non-native speakers learning English. That's what *we* are here for, not what ELU is here for. And we need to focus on *us*.

1. "But look at this great question on ELU! I wish that had been posted here!"

    We need to stop thinking like this. We are not ELU, we are our own site. There are indeed great questions posted on ELU that could have done equally well here. But you know what? *We get great questions too.* We need to focus on what we've already got, and answering those questions to the best of our ability. For the cases where a great question is *off-topic* on ELU and on-topic on ELL, it will get migrated to us. But if not, just be happy that you found a great question on ELU for its own sake; don't start wishing every ELU question that's on-topic on both sites were posted here. It's not productive, and it isn't going to happen (especially since ELU is the more established site, so it's more likely that overlap-area questions will end up there.)

2. "But users are getting confused about where to post their question (ELL or ELU)!"

     Yep. This is going to happen. *There is always going to be overlap.* There are a lot of sites in the network with overlapping areas of topicality (Programmers and Stack Overflow, Math and Mathematica, Sever Fault and Webmasters, Freelancing and The Workplace, Science Fiction & Fantasy and Movies & TV and Anime & Manga, and many, many more; just about every site in the network has another that they overlap with in some fashion, just maybe not quite as obviously as the ELU/ELL overlap is to us).

     More importantly, *this is okay*. People are going to get confused and post their question to the wrong site. And if it's a good question it'll get migrated, and they'll learn (or not). Either way, this really isn't a huge problem (and SE sites deal with it every day). People still post questions that belong on Programmers to Stack Overflow. No one is suggesting a scope change for either of those sites because of that (at least as far as I'm aware!). It's part of being a member of the SE network. Keep the great on-topic questions, close the bad ones, migrate the good off-topic ones. This is a feature, not a bug! We don't need to solve the problem of people posting a question on the wrong site, because SE has already done it for us. Topic overlap is okay.

But you don't have to take my word for it that topic overlap is common and expected—you can read this great Stack Exchange blog post called ["Respect the community—your own and others'](http://blog.stackoverflow.com/2012/03/respect-the-community-your-own-and-others/). The whole post is worth reading, and explains what I'm trying to say better than I ever could, but here are some key excerpts (emphasis mine):

> Before you can decide where to ask, you need to know who to ask. And **who you ask will depend (at least in part) on who you are***…

>That’s the philosophy. Putting it into practice creates a few wrinkles: some sites have overlapping communities; some sites are named after their audience, but the name doesn’t quite match up to how the community actually sees themselves; in some cases, the community is defined purely by a topic of interest and not any particular occupation or field. These ambiguities lead to some undesirable behaviors:

> **Scope [Gerrymandering](http://en.wikipedia.org/wiki/Gerrymandering):** ***attempting to micromanage what’s on-topic in order to avoid overlap with other sites*** or simply drive away users seen as undesirable.

<break>

>As members of a community, your first loyalty should be to that community. When evaluating a question, you shouldn’t be looking to push it off on some other site; instead, ask if it could be appropriate and on-topic for you, the experts who the author decided to ask. Be a bit jealous of your site – don’t blithely turn askers away simply because their question could be asked somewhere else. Don’t hit them over the head with your scope, help them tailor their question to fit into it – and **if that means your site’s scope overlaps a bit with another site’s, so be it.**

<break>

>**Don’t attempt to scavenge on-topic questions from other sites by asking the moderators there to migrate them to yours.** Again, there’s no harm in leaving a comment suggesting that a question would be a better fit somewhere else. But **focus on the questions that aren’t on-topic, or aren’t getting answered** – snatching someone’s question (or answer) away without any forewarning is a slap in their face.

##Conclusion##

I think I've said all that needed to be said, and if you've gotten this far I don't want to press my luck by adding too many more words! In a nutshell, I think we're doing great, I think that being a site for non-native speakers learning English is the point of our existence, and I really don't feel we have a problem here. We're going to have growing pains, and it's going to take hard work and serious reflection to get where we need to be. But we're going to make it, and we can do it based on what we set out to be: a site for *people who are learning or teaching English as a foreign language.* And if the road to graduation is more challenging than we thought it would be and we sometimes struggle along the way, hey; [at least we're in good company](http://stackexchange.com/sites). :)