Hildolfr : Just before I saw your reputation bonus (thanks a lot by the way!), I actually thought about the female Thor thing and how that matches up with my views on female protagonists.
I don't know why specifically "the majority" is having a problem with this, although I can guess what a lot of the textbook objections are, and they come back to the same tired mantras. For me, I place this situation in another category. I am not particularly enthused about a female version of Thor, but with qualifications.
If they are simply doing a replacement? As in the female Thor is suddenly supposed to have been Thor the whole time, or otherwise makes the original Thor an afterthought or something else? No go. That's just lazy, and it will likely take deus ex machina to pull that off. I see that exactly the same as I see all of the sudden switches in dedicated heterosexual characters in shows like True Blood to suddenly gay curious or outright gay characters, dreaming of gay affairs. It is simply bandwagon PC B.S.
If there is a "role", as protector of Asgard that falls to "someone", and that "someone" used to be a guy named "Thor", but is now passing as a role to a woman, I'm cool with that. But that woman should not be named Thor. Setting aside how abominably horrible a name Thor is for a woman, there is already a Thor, and he has not exactly let the name go unheralded.
So is "Thor" a title/position, or a proper name? If the former? Then so long as it is explained responsibly and intelligently, and not phoned in, I can get behind it. But if it is a proper name, than this is a direct replacement and as such not only disparages the original character, but does no favors for the female character being introduced either. It is depriving her of her own identity.