This question made me wonder why each site has its own chat. Since chat features multiple rooms, it already handles multiple topics and sub-communities.
The problem with multiple chat sites is that you might not be able to find what you're looking for, or you might be unsure which room in which site is most appropriate. You also risk fracturing the community (to a far greater extent than you do simply with SE sites, since each chat can have lots of rooms).
So what are the benefits of per-site chat? Is it best that it stay this way, or do you think it should change?
Edit: shame on me for not noticing that SE sites are lumped together and SOFU sites are not. Same question, though: why not justonechat.thewholedamnsite.com?