Merry Christmas Clive!
So the forums will stay at what it is, a place to discuss things. The Features section can still have threads related to current features or discuss new features in depth. The BitBucket page is to just keep track of everything, however "add feature a" isn't necessarily descriptive or even helpful. The forums can be to discuss features that are in the BitBucket, discuss new ones before adding them etc. The BitBucket link is being pushed because its new, and not a lot of people even know about it. It's there just so Jason doesn't have to take time to add everything. It still needs to be pruned every once in a while but this is a much easier task and most users can search keywords before adding this. Though... lets be honest, a lot of users wont. ;)
As per format, the forums don't really have many rules other than don't be a complete and utter dick, don't be racist etc etc. I don't know how it will be handled, but I think something similar to what you propose is a very good idea. It's just getting people to know about the rule, know about BitBucket and then follow it. I think the Report Issue / Feedback button needs to be renamed, though most people probably ignore it as is. It's.... stupidly tricky. I like being able to have a discussion about anything, including a discussion on having discussions. xD I think that is a very good thing that is fostered on these forums and I still think that even though I get, lets face it, jerks. Sometimes people don't want to hear a truth, don't want to see another way other thinking (not that anyone here forces their way on to someone else) or simply be told no because they feel some sort of ownership and entitlement. So yea, the current sub sections of the forums still have meaning, all of them. They just need to evolve like the team behind this software evolves and like the software its self evolves.