Tell that to the Senate and Harry Reid, something tells me they didn't get the memo. Of course you want to paint yourselves as the party of center and compromise. That's an old song and dance, you've been doing it for a decade.
Conservatives nominate people like Bush, self described "compassionate" who expand government and provide massive entitlements such as Medicare Part D. You rail against them as normal foes, instead of the moderates they are. That way when you look at a real opponent you can call them extremist. Such nominations also work for your moderate shtick, when you paint men like McCain or Romney as normal. They are much more agreeable to you than a Tea Partier, or a Libertarian. You know those men like big government, have proven track records of compromising and working with you. So when we throw them up as nominees, not all Democrats are hardened against them.
In the Republican bid to win votes through moderate candidates, you'll point out that Democrat voters are more open minded, by not being so opposed to those candidates. It'd be hilarious, if it wasn't all so transparent.
Fact of the matter is the Senate requires a super majority to get things done now, and the media allows your Senate Majority Leader to ignore House bills without a vote. Polarization is hyper charged thanks to modern communication. Local intricacies and varied interests give way to the Party Line. Because the Party can better coordinate and communicate to all members nation wide. We are all bathed in their propaganda, and we all march stronger to their beat.
What you're really witnessing now is the infantile development of a connected human civilization. It's going to take time to evolve and move past Republican and Democrat.