Most of us using bbpress are using wordpress as well.
Are you sure?
I would like a great degree of integration too, mainly blogpost/topics and comments/replies, but we may be in the minority.
Most bbPress might be WordPress users too, but I actually don’t think that so many will use it together with WordPress.
Anyway, both WordPress and bbPress do everything they can in order not to get bloated. This is the job of a WordPress (and bbPress?) plugin.
I’d like to see bbPress replace commenting in Word Press. Ideally it would just embed as a plugin and look the same as the current commenting but then the comments could be viewed and managed as a forum.
If bbPress was designed to easily embed as a commenting system it wouldn’t have to just be used in WordPress either. I’m currently trying to implement something along these lines where bbPress functions as the comment system on a website so people can comment on our short films through the forum or directly on the website. Each comic/film/whatever will be tied to a separate topic ID and pull related comments. Hopefully it works because I like the way it looks in my head.