I liked McCain as well, until he picked Palin. On that day I changed my party affiliation from R to I because I knew there was no room under the big tent for a person like me.
Why do you need a party affiliation? Why not just vote as you see fit at the time of voting (i know I'm the weird one but i still don't understand this after 40 years)
The biggest reason for most people is for closed primaries, which vary from state to state. During a closed primary or caucus, only voters registered with that party can take part and vote.
While she was the alpha version of Bobert/Green and dumb as hell, she never said that. It was the SNL bit that did and many of us remember her saying it, but she didn't.
McCain is almost single-handedly responsible for helping birth the tea party in that election. He made an alliance with the growing far right (still without the official name “the tea psrty” at that point in time, but undoubtedly connected) to win the election, and they grew in power since then. Yeah, a big part of their rise was Obama being Black. But another huge piece to that puzzle was McCain making Palin his running mate.