The problem is not Obamacare. The problem is the disgusting, predatorial healthcare system in the US. The problem is that the US doesn't follow every other developed country in the world and treats healthcare as a privilege instead of a right. As such, the monopolies that run the healthcare system exploit the lack of competitive pressure since people in the hospital frequently can't "shop around" for better & cheaper service. This leads to the practice of charging patients literally 10x to 100x what things actually cost.
I think you are slightly confused. You have it right when you are talking about the lack of competitive pressure increasing prices, but the solution is not to remove even more competitive pressure by switching to one plan to rule them all, which is essentially what Obamacare does. (You can have "competiting" plans, but they have to be the same, or you get hit for having a "cadillac plan".) The solution is to restore competitive pressure by implementing things like healthcare spending accounts (HSA) etc. which would place the consumer in the drivers seat for their own care. "... but doctor, is there a less expensive med that I can take?" (or test, or proceedure, etc.)
But this is where others start complaining that this leaves out the poor, etc. since they can't afford to contribute to a HSA. (I am afraid I don't have a good answer, except to say that Obamacare isn't shaping up to fix this issue either.)
Don't forget, there are people in Canada who come to the US to use our "shit" system, because they can't get care in a reasonable time-frame in their socialized healthcare system. It is well and good to have a "right" to healthcare, but if you have to wait in line for a year to treat something that is going to kill you in six months without treatment, it doesn't do you any good.