Maybe because OTRS is more suited for a helpdesk system (at least that's what we're using it for) and bugzilla is especially geared towards tracking bugs in software? I guess you could use OTRS as a bug tracker if you wanted to though.

The old unix philosophy : use the right tool for the right jobs.

Bugzilla is perfect for tracking bugs and issues in a software project. OTRS is a tool to communicate with people in a helpdesk style way. So it's actually a good thing they don't try to force their tool for the wrong purposes but use the good available ones for that purpose.

In Itil terms , you can only file a bugzailla bug after a support ticket has been created where you figured out there actually is a bug that needs to be fixed :)

I am not sure what this implies - since as best as I can make out, both otrs and bugzilla are ticket request system. You guys didnt really point out what in otrs makes it a bad idea for bugtracking and what portion of bugzilla makes it bad for support ticket tracking.

both can be setup to handle email processing, both have similar goals in reporting. The one major difference would be that bugzilla has a lot of addons and features that most people dont even use.