Mister Mets does bring up a good point though. Competitive primaries can be damaging-- just look at Romney '12. His opponents made personal attacks on him that reinforced Democratic narratives. People in his campaign made gaffes - such as his advisor's "etch a sketch" remark. His party's money and energy was wasted in intercene warfare. He lost his moderate image after pandering to tea parties. And his campaign lost months of organizing time for the GE-- while the Obama campaign started building up its infrastructure in key states in summer 2011, Romney couldn't focus on it until nearly a year later. As a result, his ground game suffered. The GOP has certainly concluded that having a nominee sooner rather than later would be a good thing.
What moderate image? He lost it during the 08 primaries.