Kevin Drum points out a major reason why Republicans, especially during a presidential election cycle, seem so desperately hooked on Reagan nostalgia:
After all, what choice do they have? Bush Jr. is radioactive; Bush Sr. was an apostate; Ford was an accident; Nixon was a crook; Eisenhower was practically a socialist by modern Republican standards; and Hoover was....Dubya was supposed to be the cure for this. He was supposed to be both conservative and popular, just like Saint Ronnie. But his war president schtick has evaporated, his approval ratings are stuck in the basement, and now Republicans are discovering ways to claim that he was never even a conservative anyway. Rather than building the future off the successes of their two-term incumbent president, conservatized Republicans are forced to go back to the only well they have.
Well, let's not even go there. The less said about Hoover the better. But the bottom line is that aside from Reagan, there's literally no Republican president in the past 70 years that Republicans really feel comfortable with. The unpopular ones (Hoover, Nixon, Bush Sr., Bush Jr.) are toxic and the popular ones (Eisenhower, Ford) are far too moderate for today's crew. So Reagan worship is in full swing because, really, they don't have any other choice, do they?