There are a couple of threads at the vBulletin forum regarding chat rooms. Here are the main points:
* The majority of forums reported that a chat room was very popular at the time of installation but that once the novelty wore off it fell into disuse. Others reported that it was beneficial and helped regular members get to know eachother better. I suspect that the first group had smaller memberships and less traffic.
* There is no official, supported vBulletin chat room. There are any number of third party chat rooms but only one I found which claims it can be integrated with vBulletin.
* There are security issues reported with some chat rooms whereby entire sites have been hacked by exploiting security holes in the chat room software. The one mentioned above, which can be integrated, claims to be hackproof.
So the short answer is that I have no objection to it and it could be done. The longer answer is that when it comes to operating this forum, I have no depth and am spread so thin that it most likely is a very bad idea to add a chat room. To date I have made several attempts to create that depth ... none of which have resulted in a permanent solution.