I understand the intention is to help and that I am being a drama queen. And I don't disagree that parents are generally better at parenting.
I dispute that this is a parenting decision and would say it is a public health decision. One of the goals of federal government (that most liberals and conservatives usually agree upon) is to protect the nation's citizens -- they just might disagree on the method: via an army (the GW Bush method) or through healthcare (the dirty commie way).
The other problem I have with your argument is that this is a decision government implements upon the recommendation of doctors. For the most part parents listen to doctors about healthcare decision. For some reason, some people think they know better when it comes to vaccines. I can promise you they don't. They haven't done the research (or even read the research). They are motivated by fear and the false impression that things like chicken pox and measles are not deadly diseases.
Parents can have all the good intentions they want. But when they don't have a) good information, b) reliable data, c) and a brain, they can make bad decisions that harm their children (and society as a whole). And there are certainly times when doctors are allowed to override the parents wishes, but that usually that occurs in more emergent situations like when some idiot does not want to treat their kid because they think god will handle it.