The staggering rise in pork barrel spending that occured over the last several years pretty much shows us that most of the last congress was willing to pander to anyone or anything. Majority republican or not, it was time for them to gooooo.
The fact o the matter is, once you get in politics, and to that level of the playing field, you have to make choices that you might personally not agree with. They have an image and a party to appease, which I'm sure in many cases comes to the forefront over personal opinion. If you want to get ahead in your party, you have to be a good boy.
Then of course there are many matters, such as those regarding technology, where these people know nothing of the subject, and just go with party lines or outside influence. I have a feeling that this is the case with many other subjects they decide as well, but nobody's going to admit it in those cases, where as with technology it's rather obvious to somebody like myself.
So they shouldn't blindly follow party lines, no, but the majority do, and always have. If it were always simply a matter of personal opinion, we likely wouldn't have political parties. If you ever watch certain political discussions, many times you'll only hear them discussing the possibilities of certain individuals, because they know they're the only ones likely to flop either way. The majority are just sheep, on both sides, and whichever side has the majority is, fortunately or not, usually the one that's going to make the decision. All of this shady legislation of Bush's that went through is fair enough evidence of that.