Encouraging people to explain down-votes
Since I started using SO I've had a bunch of question downvoted, and every time it made sense. Either I was wrong or I didn't get the question right. In these cases I would improve my answer or just delete it (if another answer was already up and good enough). If the downvote was "weird", meaning that I was sure I was right, I always ended up talking using the comments to find out why.
Recently I noticed that I get downvoted for no obvious reason. Let's take this answer of mine. It's not the best answer ever, but I think I provided a valid answer to the question. Obviously the user that asked the question didn't do much research beforehand, so I didn't took that much time to figure out how I could help him... but still, I feel like the downvote is a bit harsh, especially since there was no explanation.
To defend my answer, my point is:
"What's the difference between X and Y?
X is this. Y is that. You can see that they are different in many ways"
Some answers I gave were more complicated, like a big explanation about an IE-related CSS bug, and it's a pain to spend 10 minutes on an answer, getting downvoted and not knowing why. Was I wrong? Then what did I do wrong? And if I'm not wrong... wtf?
It's not the first time that this happens, and this always happens with new users' questions... and there are a LOT of new users. In most cases I just removed my answer thinking "meh, whatever", but I was wondering what you thought about this.
How about more explanations about the downvotes to new users?
Do you still answer newcomers' questions (because I'm seriously thinking about stopping doing that, they don't give feedback on the answer provided, upvote or accept)?
Could there be a way to "poke" the person leaving a downvote? Let's say I downvote a question, the user downvoted leave a comment like "Why?". There is no way for me to know that he asked that unless I check all the question I downvoted...
Ouch, sorry for the long question.