As far as discouraging users goes, I can see how trying to maintain a certain standard can be a bit daunting. Initially, yes the system can be seen as a bit blunt, but that's where we come in. By simply explaining that a question is unclear, or perhaps off-topic, or whatever reason the question doesn't meet our standards, it can help the user understand what is required to meet the standard.
If we do keep up the standard, then we can become more useful to users who need help, finding a question that matches their problem, and hopefully a solution, rather than trying to wade through forums containing little else than "MINECRAFT CRASHED... HALP PLZ" and "F---in noobz. Just google it!"
I do agree with MrLemon about the editing, as too much can change the entire intention behind the question. For example, going back to my Minecraft example, if the user posts little else than a crash dump and "HALP PLZ", that's pretty much considered unclear. By editing that question on little other than guesswork to fill in the blanks makes it a completely different question, and is not helpful to the OP. In that situation, a better practice would be to post a separate, different question, rather than editing someone else's.
For example, this question about Rupoors in LoZthis question about Rupoors in LoZ received some heat about the content of the question. However, the OP was pretty precise about the content of his question. At the time most people thought that it was off-topic, but instead of editing the question, which would have changed the content entirely, I asked a similar questionsimilar question (which I then self-answered).