The demonization of "flip-flopping" is so stupid. Bro, I want my politicians to change their minds when new facts arise or when public sentiment changes. The last thing we need is more dogmatic my-way-or-the-highway politicians that refuse to change their minds about anything.
While I agree with you, I find it hard to argue against the view that politicians are elected for the views they held during their campaign. They may change their mind after being elected, but their constituents that voted for them will not all change their mind simultaneously. To the ones that don't change their mind, it does appear to be a betrayal of their principles. A rational politician would not want to gain that kind of reputation out of pure self-interest.
Reminds me of Stephen Colbert's roast of George W. Bush at the 2006 White House Correspondents' Dinner:
> The greatest thing about this man is he's steady. You know where he stands. He believes the same thing Wednesday that he believed on Monday, no matter what happened Tuesday. Events can change; this man's beliefs never will.