It is more of a power grab than anything else. If the government becomes responsible for your healthcare, they will eventually control everything you eat, drink, smoke, how much you exercise, what activities you participate in, etc.. They will have a legitimate right to control these factors as the one responsible for your healthcare.
It may not be this way immediately but it is the logical progression if the government becomes responsible for your healthcare. The cost of the broken leg you suffered last year can be avoided this year by you not going skiing. You are 50 pounds overweight which makes you a greater health risk. Either lose 50 pounds this year or pay a fatass tax to cover the increased risk you cause to the system. Your genetic code shows that your offspring are susceptible to cystic fibrosis, a lifelong disease that would cost the taxpayers too much money so your fetus must be aborted. Don't you see where this is all going?