I don't understand the point you are trying to make. If Warner or Huntsman had enough support, they would have gotten the nomination. I'm assuming that your scenerio still ends up with only two candidates running in the general election, right? I can see how open primaries might give those guys more space.....but we have several open primaries now, and it hasn't helped guys like that overcome other candidates who were supported by mainstream party voters. And, on the other side, there are obvious disadvantages of open primaries. You seem to be saying that if all the primaries were open, independents could pick the candidates for the two parties....and it just ain't so!
I fought my own battle with the party regulars in 2003-2004. Do you think that if all the primaries were open we could have defeated the regulars & John Kerry for that nomination?
ETA: This seems to be a much bigger problem with the Republicans than with the Democrats.....because the Republican Party today is so much more radically ideologically-oriented than is the Democratic Party today.