Here is the problem I have. First, I am not attacking you personally, because I think you have very accurately described the intentions and mindset of those who framed and support the ACA.
-You say "I don't believe they are lying...they believe what they say." I agree with that. The people behind the ACA in particular and universal gov't controlled healthcare in general really do believe it is the best solution. The problem is that so many of them refuse to look at other data or viewpoints. How many times have we heard other options get blindly written off as "GOP talking points" "Fox News misinformation" ignorance, racism, and so forth. So while those on the left may not be lying, their narrow view and partisanship makes them no less right or credible.
-"I view this law as the best chance this nation has ever had to do something big on the healthcare front..." That's the language of political opportunity. Politicians want to get re-elected, but even more so, they want to leave a lasting legacy. They may want to help people, but many of them also want to serve their egos as much if not more so. Also, the problem with so many on the Left is that the solution is almost always: 1.) Big 2.) Instituted and controlled by the federal government. You don't get monuments erected in your name by solving problems through small, piecemeal solutions, even it would be more effective. Give more control to states? Remove barriers to commerce that would drive down consumer prices and increase access? Create a smaller-scale gov't program that would deal directly with those with pre-existing conditions without roping in everyone else? No. That would not be big, bold, and memorable. The New Deal style of governing seems to be the only one that the Democrats have known for the past 80 years. In my view, it has not been successful.
-"the ACA will be successful and the new benefits will be wildly popular." That would be great, but at what cost? Will it be because an environment has been created that no better alternatives exist? Will we wind up with another Social Security program? A program in which so many are blind to the problems because they want so hard to believe that their benefit is not a huge drain on the Treasury, and that the numbers are juggled in downright criminal ways to make it appear so? Will it get to the point that a mediocre healthcare system can not be replaced by a good one because people have become too complacent and dependent on that mediocrity?
If the ACA turns out great and things improve dramatically, I'm all for that. But I seriously doubt that will happen. It is bad legislation which is being executed poorly, and we are seeing more problems than benefits right now. At what point can we call it a failure? By the standard logic of the Left, never. The excuse will always be that there wasn't enough money, we need more time, we need more control. Probably 10-20 years from now, we'll still be hearing excuses and justifications about how the ACA is "almost there." And the country will be worse off because of it.