I thought the comic explained pretty clearly WHY they recruited him.
He has Thor level muscle combined with Wolverine's lack of inhibitions about killing. Thor, although being a warrior god, is more honorable and not as prone to killing. I'm getting the impression that Thor is going to be too busy in his own title when he comes back to be part of other teams, at least for a while. Wolverine is part of the New Avengers, he's unavailable to Mighty. People focus too much on what Tony threatened Ares with and they seem to forget that he got what he wanted: a high paying job and a way to stay in the US with his kid. Realistically, he could've gone to Canada or somewhere else if he wanted, it's not like the US is the only place on Earth.
What's disappointing to me (and I bet is a delight to others) is that apparently now the "stone cold killer" is part of the team formula. I know, I know, many of you will say that it's more realistic and that there are situations where killing is necessary. But, heroism was about not having to "go there". I guess the functional word here is "was".

More and more I think about calling this characters super-people and not super-HEROES.