Nationalized healthcare keeps people well enough to pay taxes. It is not interested in your well being. This is the path that our representatives in power are choosing to take.
Remember, these are also the same people in power that cannot decide whether you are carrying Suave shampoo or C4 through an airport. Nationalized education has also been roundly criticized as a failure in this country as well.
These are not failures along Democrat or Republican partisan lines. It is result of those guiding and controlling the system not having a vested interest in the outcome. In our current state, as imperfect as it may be, the providers of healthcare have a financial interest in your well being (arguably). However, under nationalization, your taxes will be paid regardless of your treatment. There are certainly arguments and instances on both sides that discount this position, but, the farther an organization gets from it's motivating factor, the more likely it is that the patient's needs will not be met.
The mortgage industry parallels this, in my opinion. The farther the investors got from the actual product (Homeowners). The easier it was to lump them together as numbers in an economy, rather than the elements that drive it. The farther the motivation moved away from those making decisions, the easier it was to collapse.