Romney is just too cold, caustic, and not a fun guy to hang around. He looks like a Ken doll come-to-life. He literally is not the type of guy you'd like to go and have a beer with, even if he did drink! On the likability scale, he's pretty close to Hillary (Cold Fish category). That's the trouble. Not Mormonism, not flip-flops (they all do that). It's just that he's not likable enough to forgive and forget the policy changes and weird stuff about his religion.
Went to the Hannity Freedom concert in Dallas with some other FReepers and Mitt was introduced along with some other politico figures. Romney showed up in formal suit and coat while all the rest were informal. TX gov Perry wore jeans and boots all the rest were equally informal. The contrast was very noticeable.