What exactly do you want the X-Men to do, if not deal with the factions within the mutant community?
There IS no "mutant community" anymore. There's less than 200 of the fuckers ON THE ENTIRE PLANET. Even assuming that EVERY SINGLE MUTANT LEFT moves to Utopia, where's the SCOPE? At least previous stories about the "mutant community" implied some relevance for the vast masses of non-costumed, unseen mutants out there in the world, for whom the X-Men (and even the Brotherhood, in its own way) were ostensibly fighting to support. Now, mutant-versus-mutant fights affect absolutely NO ONE other than those same less-than-200 people on a single isolated island. At least when non-mutant heroes and villains fight, there's still some implied STAKES involved, in terms of the fates of the larger CIVILIAN population. Utopia, on the other hand, isn't even big enough to qualify as a TOWN - it's little more than a VILLAGE of supers, cut off from the outside world. Aside from the already heavily-stretched loyalty that fans might feel for certain characters, why should they give a fuck if the entire fucking island lives or dies?