While I also don't like the situation with Claire and HRG "never changing", I find that it helps me enjoy the show if I remind myself that it essentially is a comic book. If I compare their relationship to, for instance, Peter and Aunt May, or even Lois and Superman, I realize that Heroes might...
I don't get it. What did future Peter have to do with Sylar getting Claires' power? If Peter does not come back to shoot Nathan, Claire would have still been home when Sylar came calling, having no reason to be worried about Nathan.