I tend to agree with the "if it ain't broke don't fix it" idea, However I would guess that a lot of people particularly newer anglers ask a question that may get swept aside by more popular posts. I'd say if you do choose to add another forum it could be a forum specifically for asking questions about techniques and methods.
Or Possibly a boating page there seems to be a lot of boat talk going on too..

As a fly fisherman I don't see the need for a fly fishing specific forum.