Because he is a true conservative, of course. No, I'm joking. I didn't just have a run in with the pod people or the now completely deranged Ann Coulter. Romney won simply because he had his wing of the party pretty much all to himself (as Huntsman skipped Iowa and dropped out before South Carolina, he was only a factor in 1 contest, New Hampshire) while his opposition was splitting the same voters throughout the primary season. For a time, Romney claimed victory in Iowa with a pathetic 25% of the vote! This is how a conservative dominated party ends up with a Dorian Gray-esque charlatan at the helm, one who despite all the organizational and monetary advantages only received 40% of the popular vote to date.
If you look back to 1980, Reagan won for a similar reason, he was really the only conservative running while a gaggle of liberals and moderates split the same vote. George H.W. Bush, Bob Dole, Howard Baker, uber-liberal John Anderson and the LBJ-like John Connally were just not viable choices for true conservatives who believed in individual freedom and small government. If 1980 had been like 2012 and Reagan had to compete against the likes of Jesse Helms, Paul Laxalt and Jack Kemp for the nomination against sole moderate George H. W. Bush, Reagan would have been a primary election footnote. The math simply would not have worked.
Why did we have so many conservatives? Because 2010 was just such a banner year that it was easy for the candidates to think that the Tea Party would help propel them to the nomination and the Presidency. People who were obviously not of Presidential timber or gravitas like Herman Cain, Michelle Bachmann and Rick Santorum threw their hats into the ring thinking that if they could just outlast the others, they could do it. There just needs to be a way to structure things in the future so it doesn't happen again or else we will be stuck with the likes of Mitt Romney and his vacuous minions as our "representatives". Maybe a national conservative pre-primary primary to help focus on one candidate? Or a national Tea Party nominating convention before the primary season? I realize this will be difficult as we are all free thinkers and we just might not cooperate if our favored candidate is told to quit the race early in favor of someone else. Plus, let's not forget the inflated egos of the candidates themselves. This might end up being a pipe dream but having some sort of gatekeeper to make sure only one conservative gets through to the actual primary process will probably serve us all a whole lot better than the way things are now, a general election between Tweedle Dum and Tweedle Dumbass.