I joined up earlier today, and I think it's quite a nice idea. As people have said, this kind of thing has been done before and while some of the forums of this kind have either immediatly failed or gone down over time. We can see how this lasts for now though, yes? They are nice places to just kick back with NG users without the bad things about the BBS subculture getting you everywhere.
I don't think it's really about elitism or anything, it's just a place to come when you might be banned from the BBS here or you just want something slightly different. The reason why people make these things is, in my opinion, due to constant complaints (for lack of a better word, it's not always done for bad reasons) about the BBS. These complaints may be stupid in some cases, but if it's what lots of people want, I don't see the harm. Look through the Open Discussion thread alone, and you'll notice people are always asking if a more exclusive forum area can be added for regulars/older people. It's unlikely that's going to happen, so we have fan-made forums elsewhere.
I mean, I've only been on it for a day. It seems pretty friendly so far. Come and join if you want, but I don't think people do these things just out of spite or anything. Eh.