It makes sense to handle the taxes for something like healthcare on the national level because people aren't going to renounce their IS citizenship to avoid their tax obligation, but they may move to a different state.
But if I want to move states and forego both the costs and benefits of socialized medicine, why would some one care? Why make some one who does not wish to work under that system do so? Again, the only reason is because you wish to force your position down some one else's throat via the tyranny of the majority.