In the context of the effect they have on the industry, of course they should be discussed. But I just don't see myself participating in a thread about my experiences playing Temple Run.
They talk about casual games, at length, on the Giant Bombcast all the time. It's actually where I learn about most of those games, and some of them would have gone unnoticed by me otherwise.
Also, posters like me who don't want to discuss those games =/= fostering an exclusionary community. I don't think anyone would be offended if they saw a new Temple Run thread and demand that it would be closed. If someone is enthused about it and wants to make one, go for it.
It's only one of the ways that people on GAF are exclusionary (other posters in the thread have already pointed out some of the other ways).
But demanding that a Temple Run thread be closed sounds extreme. If you don't care about a thread, why try to bring it down rather than stay out of it? Unless you somehow typoed that.