Let's imagine a Republican National Convention with no majority nominee on the first ballot. How do we think the first ballot will wind up? There are only so many candidates that are capable of getting enough delegates to stop that, so I expect the delegate count would wind up in the neighborhood of Newt Gingrich 40%, Mitt Romney 40%, Rick Perry 10%, Ron Paul 5%, and scattering votes making up the remaining 5%.
Even in the unlikely scenario that we get no majority, how do we stop Mitt Romney (or Newt Gingrich) from finding the votes he needs simply by picking up delegates for whom Romney is a second choice, plus making promises to spend X number of dollars campaigning in selected states this cycle in order to win over party officials from various states? That's a maneuver described to me by a friend as Pawlentying the vote.
Once the convention gets control, the voters lose any say. Though I think such an event is unlikely, it still troubles me that anyone would root for it.