Aggressively closing duplicate questions
I think the vote to close could be bit better.
I know people (me included) can be too lazy to ask questions that should not have been asked because they are duplicate or something else.
At the same time I think people can be too lazy when closing the questions. I don't think this scenario is uncommon. One user comes along and finds a question that he thinks should be closed. The next user sees the question and sees that someone has voted to close, so he does the same thing without thinking too much about it, and soon the question is closed.
Perhaps discussion about it before a question should be closed is too much, but I believe that it should be more difficult to close a question that already have multiple answers and views.
Perhaps giving the user you asked the question a second change to be edit the question.
At a minimum I think you should be required to leave a comment when closing a question, perhaps not all 5 users, perhaps only the first 2.