I think we can both agree that unquestioning acceptance of authority generally has detrimental effects. However, this does not make the converse true; unquestioning defiance is, at its core, no different from unquestioning acceptance. Sometimes the government happens to be correct about a particular set of claims. The "medical establishment" consists of countless immunologists, pediatricians and public health experts (just to name a few) who all know things that the general public does not. Plenty of these experts have given and will give vaccines to their own children, and there does happen to be a broad consensus on the vaccine issue, making the probability of one giant conspiracy that spans several disciplines highly unlikely.
By no means do I intend to suggest that 100% of vaccines are necessary, nor do I think vaccines are safe 100% of the time (some people have them administered in potentially harmful ways, such as getting several of them in one doctor's visit). I just would caution against the attitude that some "anti-vaxxers" seem to have, which is that being contrary is objectively beneficial. For them, it becomes an ego thing rather than a viewpoint based on scientific reasoning. It's the difference between, on the one hand, people simply declining a doctor's advice - and on the other, joining movements literally defined by contrariness, buying products shilled for by the leaders of these movements, and becoming preachy to others from a moral superiority angle. The latter suggests a need for self-justification.