Re: Hack to remove /forums/forum/
If you did what you want to do,
bbPress would have no way to tell if
example.com/welcome-everyone
was a sub-forum or a topic.
In WP you need some way to determine if something is an archive view vs a post. ie. example.com/archives/monthly vs. example.com/monthly (which would be a post) It’s the same logic with bbpress.
However it might be possible someday to easily change /forum/ and /topic/ to something else. Removing them is impossible.
If you move bbpress to your webroot, you will get rid of /forums/ but it cannot co-exist with bbpress in that way as you cannot have two index files (without super-integration which is ill advised).
BackPress might solve this however someday.