http://bugs.winehq.org/show_bug.cgi?id=35450
--- Comment #1 from Austin English austinenglish@gmail.com --- It would be quite a pain, we'd have to move all old bugs (including closed bugs) to a new 'version' (pre-1.0 or something like that), which would cause a lot of email notifications.
Additionally, the version is supposed to reflect the first tested version of wine that has the bug. Changing all those versions would make it harder to determine that for older bugs. That said, I don't know of anyone actually running reports/queries on old bug data.
I personally don't think it's worth the effort. I'm open to discussion though (which should be on wine-devel, not bugzilla).