It's neither a good or a bad thing.
The US system isn't the only way a marketdriven system can be and a lot of it's problems are lobby and politics related.
Market demand is a good thing in the sense that it creates better allocation of resources.
The US doesn't have a healthcare market driven by market demand. But the fact is that the US system has more advanced treatment methods.
The problem is that it's not evenly distributed.
Why is market demand a good thing?
In the US the government spends more per capita than France, but gets worse health outcomes.