I think the GOP's biggest problem was overconfidence.
They just couldn't imagine the country re-electing Obama given the jobless rate and state of the economy.
So, instead of worrying about electibility and moving a few inches more toward the center, they got involved in a long and expensive primary battle, and their platform, if anything, moved further to the right.
Romney attempted to move back toward the center, but he had to move so far that he looked wishy-washy and inconsistent.
The 47% remark was a devastating torpedo.
Add in the rape remarks of a couple high profile candidates (and they happened just at the point when a lot of undecideds were making up their minds.)
Add in the loss of momentum with Sandy. And the NJ governor working hand in hand with Obama - which didn't help the GOP argument that Obama was not capable of any kind of bipartisan action. And the memories of how Bush messed up with Katrina. (When the GOP was doing everything humanly possible to distance itself from Dubbya.)
But the killer, I think, is that they underestimated Obama's "ground game" and his ability to get his constituents out to vote. In that regard, the youth of the democratic party is a big advantage. Energy, social media, neighborhood organizations, etc.
Given the fact that evangelicals make up such a huge portion of the party, I doubt that we'll see the GOP move very much on the kinds of social issues that are involved there.
More likely, they'll soften on immigration and make a play for the Latino voters. Bush did much better with that demographic and it got him elected twice.