I'm concerned. Most questions that end up as bug reports, don't start out as bug reports. They start out as questions and the bug report is the solution to that question. It's far better to pester the individual who posted the question, to select the appropriate answer, even if its a submit the bug report to… then it is to close the topic as non-related.
For example Problem with Freemember register form! [closed], not to pick on Adrian, since he's following the ideas generated here, but this question is a valid question that also has a valid response, that can be selected as the official answer to the question. But worse yet, the reason why the item is closed is 'invalid', at least from my perspective. That's kind of mentally horrific to my perspective of the site.
Is it reasonable to tell people that a question involving a PHP Error
is invalid, because the issue is related to PHP and not supported here? ExpressionEngine is a PHP Application, every third party add-ons are PHP applications, by its very nature EESE should deal with PHP errors, so long as they are related to EE or an add-on. General PHP errors could be moved or closed as non-relevant, especially if an answer was never provided or selected by the user.
This also concerns me, because some third party add-on developers have decided to use the EESE site as their primary support solution. I think this is great. I'm not a big fan of GetSatisfaction, though I do like UserVoice. But I'm more of a fan of a central repository of EE knowledge (Q&A) and other details. I feel like EESE CAN BE that central repository in ways that the Ellis Lab Forums can't be, so I'd much rather see the response that this was a bug, rather than this was closed for being off-topic.
I salso agree with Mark and Adrian, that to the best of my knowledge, items closed for being off-topic eventually fade out of the system, at least they seem to at other StackExchange sites. So, then that defeats the knowledge base components of the site.
I'm all for keeping our stats up, but not by any means necessary. Abandon questions with no response, sure close them. Abandon questions with one or more good response (keep) and encourage more voting up of the best response. People are smart enough to know that a response with 3, 5, 10 or more votes is a good response and that they can give that response a try. But if a response CAN'T BE closed as 'bug report', then don't close it for untrue reason. I think in those situations, it would be better to 'collude' (in a more positive sense) with moderators to up vote the answer, that works, if the questioner has seemingly abandon the question.