Because the national election is hugely different than the primary season. The primary season is a series of states across of period of 3-4 months. The national election is based on a one day vote by the entire nation.
Because the intent of the primary campaign is select the candidate who best represents the sentiment of his party AND has the best hope of winning the national election, it is important to have a system that does not permit any candidate to win without hearing from the entire nation.
I agree that the primary system has to be changed so both parties end up with a nominee who represents the vast majority of their respective bases. Maybe, instead of by ‘county,’ an allocation could be done by Congressional District since CD’s are population based and roughly equally populated. Winning 50 of 60 counties doesn’t do much good if 90% of a state’s population is in the 10 counties. But if one candidate wins 7 of 10 Congressional Districts in the primary, it’s a precursor of how s/he might do in the general election.
One helpful change would be having the earliest primaries in more ‘belleweather’ states, i.e., Ohio, Missouri, and having a range of states, not small states ... especially IA and NH that are now pretty solidly blue. Maybe we could have an early primary in AL or MS as well.
There is a LOT of room for improvement in the process, but it would help if conservatives and/or Republicans could get behind one candidate, independent of the primaries. In ‘07, all I saw conservatives do was trash Rudy Giuliani who was in the lead in most polls. There was a bloc for Hunter, and beyond that very little solidarity. The ‘voices’ of conservatism, i.e., Rush/Sean/Mark didn’t focus on any single candidate and refused endorsements till it appeared McCain would get the nomination. By then it was too late.
We also have to be willing to sacrifice ideological purity if it means having the 3rd most conservative candidate win the nomination if he has a chance to get elected, rather than the #1 most conservative who doesn’t stand a chance.