The core group wanted to add them and would have until Rick went all nuts.
Agreed, but their bowing down to him will be costly. They should have stood up to him at that point.
When they all voted to kill the kid it was essentially Rick and Shane arguing for it while only the old guy was against it. Being compliant in immorality and bad decision making isn't exactly a noble virtue.
Like I said I love the show and the moral philosophical questions it raises, but on a character level I'm not seeing much of a difference between the Rick gang and the Woodbury gang. They all left their morality, whatever they had of it, at the door a while ago.