I suppose a request could be made, if you have a good enough reason for it. Mainly, groups are there to provide easy administration. It's easier to create a section of the site accessible to a "group", and give permissions and settings to the group, and then make members part of a group, than it is to grant permissions to individual members over and over.
Not necessarily "elite", but yeah, you get the point.
Members of the "Staff Writer" group get 1) a user profile badge, 2) access to the Staff Writer's Forum. As an administrative task, it's easier to assign those rights to a single thing, a group, than it is to assign those rights to X amount of users.
So, any Group formed would have to have something more within the site than just a shared interest. I think simply having a new forum added to the Coffee Shop area for Game Developers would work fine in your example - no need to create a vBulletin "Group".
Many forums create publically-joinable usergroups (such as a Game Developers usergroup) that any member can join as a secondary usergroup. Usually the advantage to being in these publically-joinable usergroups is just a cool badge, but it does let people with the same interests easily find each other, as you can search the memberlist by usergroup. It's all up to the specific forum to decide what they want to do with this vBulletin functionality - but it comes down to there being 3 different types of usergroups: Admin-specified usergroups such as moderators, where only admins can add users; Publically-joinable usergroups that users can request acceptance into, and need to be approved by the group leader before they're admitted; Publically-joinable usergroups that anyone can just let themselves into.
For example, we may make the Staff Writers usergroup a publically-joinable usergroup that would allow anyone to request admittance. It would then be up to the group leader, Davey, to accept or reject an application.
I just suggested ways I've seen other forums use vBulletin groups. We don't really have a need for many usergroups ... aside from the obvious (admin, mod, supermod, regular member, banned member) we have a usergroup for Sponsors, a usergroup for Team Colleagues, and a usergroup for Staff Writers.