I find that some questions that are voted off-topic most certainly should be; for example if someone is asking something that can be easily looked up in a dictionary. On the other hand, questions that are too open-ended are often indicating a deeper unasked question that is more specific.
This is the most recent example; I am impelled to post this because I have found myself writing useful answers to questions that are under consideration for closing on several other occasions.
The OP is asking if we might come up with some cool expressions that will impress the jury on his writing exam. Of course, that's too open-ended for us to be able to come up with anything useful. However, the OP is laboring under the misconception that he needs to find some fancy expressions that will impress the jurists in order to get top marks. This is obviously untrue, so he can be usefully told that he needs to focus on stating his position clearly instead of writing to impress. Since this may not be true in the poster's native language (their local culture might place an emphasis on beauty over clarity, for example), it fits the purpose of ELL to make this clear.
People often come up with "half-solutions" to the problems that they perceive, describe those half-solutions, and ask for help on making them whole. In such a situation, it is often the case that the half-solution is entirely the wrong approach. If we are to help as well as we may, it is often necessary to step back and assess why they are asking the question, and answer in such a way as to undo a misperception further back in their line of reasoning.
As a general point, I submit to the group that looking for reasons to vote to close is not as conducive to growth as looking for reasons not to. I'd like to suggest that we work a little harder to "read between the lines" and pull out the underlying question that is really being asked before voting to close a post. While discouraging "help vampires" from wasting everyone's time is a great idea, driving people away when they are sincerely interested in learning is a bad idea.