How can you reason that the ACA was caving in to republicans when none of them voted for it? The reason why we got the crap that we did was to get the moderates of his own party on board, which they almost failed to do anyway (see Nebraska). They never would have agreed to a single-payer system, and this was the best they could do to try to get coverage for everybody.
Where were you when they were drafting the act? The reason we got what we got was the Republicans were given an equal footing at the drafting table. There were 6 Democrats and 6 Republicans drafting it in the false belief that if they had a hand in making it they would support it. The reason it almost failed the Senate was totally Harry Reid's failure to take Mitch McConnell at his word to "make sure that President Obama was a one term president" and use the "nuclear option" to fix the filibuster rule at the start of that session. Even to this day it still hasn't been fixed.
The only reason the Republicans are fighting the Patient Protection and Affordable Care Act (the FULL title of the act) is their fear it will be as popular as Social Security and the fact that President Obama was backing it (at that stage I argue he would have backed anything that had a positive effect on the broken healthcare system we still have).
The insurance companies are against it because it requires 80% of the premiums be spent on healthcare while trying to eliminate the arbitrary denials. The doctors don't like it because it requires them to be more transparent and stop unnecessary tests that only line their pockets. It also cracks down on the waste, fraud and abuse by hospitals. So that is why they are against it.
Meanwhile, millions of Americans now have some form of healthcare that they could never get before.