Precisely, and great insight. That line "just when I thought I was out, they pull me back in" was perhaps two films too late.

Up until Vito's shooting, Michael was a bit more cavalier about the family and would have been more content to be an American -- going to Dartmouth, enlisting in the Marine Corps, having the WASP girlfriend, et al. He even skipped Connie's wedding ceremony. And to Vito and others, they were content to keep him out of things and keep him on the "legitimate" side of things.

Vito was shot, and you're right - Michael had to save the Corleone family. It was for the noblest of reasons - family preservation - but Michael's metamorphosis had begun. The Corleones were saved, but Michael went from a good-natured, quiet kid to ruthless and evil. And even when he was trying to do good, he came off looking worse (his veneer of legitimacy and his donations and whatnot between GF2 and GF3). And in the end, he ended up losing everything - his life with Kay, his dreams of legitimacy and in the end, even his daughter.