For me the problem lies not with the fact that Thor can be overpowered.
I think there really shouldn't be any characters at all that can't be threatened on some level... Otherwise they'd be boring.
The built in weaknesses for Superman, for Silver Surfer, Sentry... Whether it be elemental, physical or psychological there is always something to balance a character out.
Thor has always been a force of nature, a god-tier hero, he was long awaited and then came back, and we were all grateful that the person who brought him back respected the craft, respected the character.
Straczynski built upon existing mythos and brought Thor to the next level, he's more omnipotent then ever.
Everyone has had a sick feeling as too how Thor would be used in other titles, especially considering he's been treated so well in his own.
Now we have a situation where Thor is crossing over into the title of an uninspired character written by an unpopular storyteller.
Now we witness Loeb basically use all the Straczynski build up to his own stupid advantage so he can further drive home the point of how XTREME AWSUM red Hulk is.
Red Hulk is a massively powerful character, and to what end? Whats his bloody point, he isn't massively powerful in any interesting way, I think I'd be raging less hard if I'd seen something similar involving the Sentry and a well crafted story.
My stomach sinks even more to think of what Bendis has in store for us...