Nice layout on the Dean Robinson site (linked above). I think that’s probably a large part of the answer, it’s about how we present groups / forums to our users. A lot of usability is tied up in the presentation – something I’m having to work on for my own site.
@D Cartwright do you need to completely hide the groups, or could you just remove them from the menu(s) if you only want users to use the forums? Or turn groups / forums off and install stand-alone forum even?