There’s considerable unnecessary nuisance around people leaving a group. Best way to fix is similar to WoW (you should pardon the expression): Person starting group is designated Leader until he leaves group, then the next-most senior member inherits leadership. That way, losing a member in an instance will not be so disruptive because the group owns the instance, and if a person goes off-line without remembering to surrender group membership, we don’t have to dissolve and re-form the group to reclaim his space.