Re: Thor
I agree that that's sloppy. But I don't think it's a huge leap to think that Thor learning that "might does not make right" would lead him to decide they should not annihilate the entire frost giant race. How simple do we really want our movies to be?
The real mistake was probably in portraying the frost giants as blue orc monsters. If they looked more like humans and Asgardians, the connection would be clearer.
SPOILER --> Plus, Loki's parentage would make more sense.
I don't have as much of a problem with Thor's growth in that regard as with how that growth is ultimately borne out in the climax. If the threat was on Earth, and if Thor had to realize that annihilating his enemies was not worth destroying so many innocent lives, I would have liked this film a lot more.