It's certainly sub-optimal, but they're far better organised than the Democrats. And they're winning elections and passing policy they otherwise wouldn't because of it.
Name a major piece of legislation they (the GOP) have passed in the last 4 years. Than look at what the Democrats have passed.
Until you can explain how this effects what we're talking about in the slightest, you can stop saying this. As far as I'm concerned it's just a red herring.
In addition to what Canadian Mojo posted the US system also makes it that politician are often more apt to side with the voters in their state or district than the party. That is why you had Dems like Bill Nelson not wanting to vote for health care reform. It was unpopular in his state, if for nothign else than wanting to keep his job he was representing the voters in his state.
The US system normally can't move as fast as a parliament system but in turn it is also less likely to have wild knee jerk changes in legislation. If the US was a parliament system it is likely the Dems could have gotten true universal health care, it is also just as likely that the GOP would be able to do away with it. Right now the GOP would have to keep the House, take the Senate with a super majority and most likely also take the White House to kill Obamacare.