Only a couple simple reasons...

• The cost of healthcare as a percentage of GDP is increasing as an unsustainable rate. Legislative action is needed to bring those costs under control. The free market has not accomplished that in over thirty years and there is no evidence that it can or will in the near-term future.
• Americans are not counted among the healthiest populations on the planet, not even close. That's in spite of the egregious costs we incur for such care compared to other countries.
• For a country that counts itself among the best educated and most economically advanced to have tens of millions of its people with no healthcare whatsoever is almost criminal to think of. Something needs to be done about this problem.

If you can think of other ways to solve these problems other than a comprehensive new set of laws and regulations, and probably taxes to pay for them, please share them with us.