I do believe all people, even politicians, should have the leeway from others to develop over time. Man, if I got boxed in based on what I said or did 15 years ago... Yeesh. What matters to me is what direction people move in.
Listening to the old Bush, I was thinking, "Hey, he's not so bad." The new Bush strikes me as somewhat evil. That's not progress. Kerry has evolved into more of a politician, for obvious reasons, and he's not my favorite of the (former) democratic contenders (by a large margin), but he's certainly evolved in a way that is far more acceptable to me than Bush.