Do we not already have a significantly moderated political system? Two parties representing a general left-right divide? If one party isn't restrained from within, typically the other party will create balance by taking power. What sort of political system would we have if the out-of-touch insiders of No Labels persuaded us to cede debate without making our ideological cases? Is "moving forward" for the sake of moving forward a virtue?
Finally, No Labels also claims that "the consequences of inaction have never been greater, because the issues we face have never been more serious, more complicated, or more dangerous."
Admittedly, I'm no Will Durant, but I find dust bowls or tens of thousands of corpses on the beaches of Europe to be as complex and dangerous as controlling debt. Actually, a lot more complex.
Not to mention, most of that debt was the result of the wonders of bipartisanship.