That's been standard procedure for issues getting a lot of off-topic comments, or have the potential for the same, for some time, and it's definitely welcome when trying to track the status of popular features/bugs. The point of issue comments is to contribute to getting an issue fixed or resolved, not to act as a discussion thread. It's quite clear this was a done deal for some time and there's nothing further to discuss in that issue.

Especially given that every comment gets emailed to everyone who'd starred the bug. Leaving comments open (and receiving "BUT WHYYYY" comments) just annoys the hell out of everyone who'd starred it.

Once a decision is made, further discussion is waste of everyone's energy. If the decision weren't final, the bug would remain open. People can post angree screeds elsewhere, like on their blogs' RSS feeds.