I will not use any chat system that's not XMPP based. Seriously, I'm tired of having to have a special account on a special system that doesn't interact with any of my other software in a reasonable way.

The chat problem has been solved, and for better or worse, it's XMPP.

As for whether or not it's needed, I have no idea. Personally I don't see why there's any need for 'discussion' or 'community' on a site that's supposed to ideally be a collection of largely anonymous oracles. In fact, it seems quite highly counterproductive to that goal.