The other chief reason we should not ration health care is that it is immoral to do so. As my friend Eric put it yesterday, selecting who gets what treatment on the basis of age or health status "smells a little too much of Auchwitz" for comfort. The value of a life becomes less than the value of our life.
I am happier with the principle that we're not going to leave anyone on the battlefield. Anything less is unworthy.