The core of the ACA was a Republican proposal (started under Nixon, then elaborated under the AEI, then implemented in MA by Romney). There were HUNDREDS of meetings with Republicans negotiating the substance of the ACA, and dozens of Republican amendments that were accepted into the ACA. The fact that at the end of the day Republicans all voted against the law that they helped write doesn't mean that they had no influence over the contents of the law, just that they ultimately thought that it was more important to try to block Obama from passing anything, no matter how much be accommodated what they claimed they wanted.
If the ACA had had no Republican input, it would have been a few sentences long, cost ½ as much, and been much easier to implement. That is, eliminate the age minimum for Medicare so everyone is allowed to buy into it. Nice and easy. But with united Republican opposition to any improvement in healthcare in the US, a few corporate Democrats (e.g. Lieberman) were able to screw everyone in order to improve profits for a few friends.