It'll depend on who is reading it. Inserting words for the sake of the word count is almost always a bad idea.
Ask yourself why your essay is so short. Is it because you aren't saying much? If so, then think of more to say. Don't forget that you don't have to actually answer the question. You can instead use the question to lead into your sales pitch.
If, however, you've said everything you want to say and you are still at 3,000 words, then maybe you are just a succinct writer. Consider yourself lucky to have that rare skill. The people who have to read all those dang essays will certainly be glad. 🙂