I don't even get the chance to vote for Thompson, Edwards, Giuliani, et al.
Why because someone in Florida, South Carolina, Iowa, or New Hampshire says I can't. Not exactly the way I see the Constitution: some get to vote and the rest don't.
If we were talking about RKBA issues most would be outraged that only a few got to make the decisions while the rest of us pound sand.
Well, the Constitution doesn't say
anything about getting to choose from a wide range of nominees among your party. Heck, it didn't say much about who got to vote in general Presidential elections right off the bat. You still have every chance to vote from among anybody that chooses to get their name on the ballot; or, alternately, you can write in anybody you choose. There is nothing in particular keeping Thompson, Edwards, etc. from getting on the ticket as an independent or from another party, unless perhaps your state won't let them (in which case that's an issue with your state, not New Hampshire or Florida).
I know for certain that the Constitution says precisely jack squat about how the Republicans or Democrats (or any other party, past present or future) chooses their nominees. It doesn't say anything about political parties in general, to my knowledge...but I suppose I may be mistaken on that one.
The Democratic and Republican parties are private organizations, and they can choose their nominees as they see fit. If you have an issue it's with the Republican party [EDIT: or Democratic, sorry for presuming], and the Constitution has very little to do with it.
Also, between SC, FL, NH, IA, NV, etc. you're actually starting to get at least a somewhat broad cross-section of the country...so anybody lagging after those five states should probably consider dropping out anyway; they'd probably not have fared well on Super Tuesday. But regardless,
nothing made them do so before then; they could easily have hung in for as long as they chose, just as Huckabee and Paul have chosen to.