On a forum for learning Japanese, I think that when an answer is down voted, it should require a comment to explain what the issue in the question or answer is.
I understand the premise behind the voting system, but what good is having someone who potentially does not completely understand Japanese, down voting an answer b/c they think it is incorrect? Others (who may also not completely understand Japanese) then look at that and if someone else feels it wrong even though the answer is in fact correct may jump on board and down vote as well, which then perpetuates that the answers content is incorrect. It goes against the whole system that the correct answer will rise to the top.
If an answer is down voted for incorrect content, it should be pointed out to the poster so they can adjust the answer or delete it if they find they did not really know the answer. If it is voted down not for correctness of content ,but some other reason, someone looking at the answer may be confused that the answer is in fact incorrect.
If making compulsory comments is a no go, how about making it compulsory to have to put a reason in with the down vote and have several of the higher rep users or mods decided whether it is a satisfactory reason.
As it stands, this site is not going forward. I have only been here a few days and I deciding whether I should stay or not.
Not very good at all.