Bush is actually a pretty moderate republican, and probably pretty electable, but the fact that 2 other members of his immediate family were presidents themselves just is so distasteful to me. In a country of 310+ million, that's the best the GOP can do? What's that say about the GOP?
It says the public has been bred to like brands in reference to so-called political dynasties, hence the long decades of trying to get other Kennedys to run, and the happy feet over Jeb & Hillary from their respective camps. It takes less thought to go with someone you feel hails from a comfortable, somewhat familiar mindset, than some less popularized pretender.