Seth Masket points out that those of us who are disappointed with Romney's inability to wrap up the nomination are missing a key point about why it is taking him so long. The new GOP primary calendar is awarding delegates at a much slower rate than it did in 2008:
Why hasn't he "closed the deal"? Because this year's calendar and delegate allocation system are a major departure from what we've seen in previous years. As Matthew Dickinson points out, by Super Tuesday in 2008, more than half of the Republican delegates had been allocated. And that was in early February! As of today, only 36% of the delegates for 2012 have been awarded. The contests are simply more spread out than they used to be. And while the Republicans haven't gone full-proportional for the most part, they're not exactly winner-take-all in most of these states, either, while they largely were four years ago more states were so four years ago.
It certainly doesn't help the media narrative for Romney that he isn't winning each of these contests with outright majorities, but there is growing evidence that he is all but certain to be the nominee. (Masket links to this post by Josh Putnam which makes the mathematical case for Romney's inevitability.) Despite this guarantee, the long road to the nomination won't help fix the perception that Republicans are not eager to line up behind him.
It should be noted that some are quite happy to take advantage of this long primary season to reinforce Romney's weaknesses. Here is Bill Kristol gleefully awaiting a long and drawn out primary as Romney slogs towards the inevitable.