It's also friendlier to newcomers than bugzilla/others.
I'm quite sure that those most likely to report bugs (in the greatest majority), will be experienced open source users such as yourselves. Although a tight user base and the two support sections of the forum seem adequate for new comers in relation to bugs - they can hardly substitute for a good bug tracker. Its why they are there - too make our wonderful programming team's job easier, more manageable, and more easily "trackable".
I bug-tracker is the best way to keep a system free of bugs, and lets the users submit "requests/improvements" in a more systematic and manageable way - features that can be tracked across releases (as in a release plan etc.).
And we can still use the bug tracker in conjunction with the forums - if newcomers come in and report a bug, we can verify it and send a more detailed report via the bug tracker. Leading to a more efficient development cycle.