Why are so many people enraged by the Affordable Healthcare Act?

In his article Paul Krugman states: “Obamacare is a deeply conservative reform, not in a political sense (although it was originally a Republican proposal) but in terms of leaving most people’s health care unaffected. Americans who receive health insurance from their employers, Medicare or Medicaid — which is to say, the vast majority of those who have any kind of health insurance at all — will see almost no changes when the law goes into effect” next year.”

If this is true, why are so many so enraged by it?