I've noticed the same thing on SO. Since sometime end of the summer the percentage of good interesting question has been dropping with the current set of questions is largely populated by stupid ones. Stupid questions and duplicates are not being downvoted and closed as before. I find myself reluctant to even look inside most of them less to participate. I'm not sure if it's seasonal or not, but it's definitely getting boring, the last 3-4 weeks being the most boring time since I discovered SO.

I think community needs to take more active actions on dealing with duplicates and bad questions. Otherwise quantity will defeat quality.