Why are some parents more afraid of vaccines mentally disabling their kids than of diseases killing their kids? Not that I believe that vaccines do that at all.

When my daughter was 16 she had 3 vaccinations at the same time. Within hours she had a complete psychotic break, that she still is not quite healed from. It took her a year to come back to us, and she still has physical disabilities.

Even with that, I still believe in vaccinations for all.

Some doctor wrote about a study he did back in the 80's with very few patients that said vaccines were bad. The study has been retested several times, never with the same results. The original doctor has even admitted that the study was flawed. Yet the conspiracy theorists keep bringing it up. They say it is the mercury in it that is causng the problem. The mercury is part of a compound. To blame it is like saying table salt will kill you because it contains chloride. 

They were lied to.

I am reading the biography of Mark Twain. In 1845 he writes of a measles epidemic that was decimating the children of his town. He said that for awhile there was a funeral everyday.

We tamed measles with vaccines but if herd immunity is not maintained the virus could become as virulent as it was in Mark Twain's day. 

Some very few should not be vaccinated, but the cost to the few is far, far outweighed by the benefit to the many.

There are occasional (allergic?) reactions to vaccines that do indeed cause grave problems. Even so, the likelihood of reacting to the vaccine is far less than the chance of contracting the disease if the vaccination is refused -- as you implied in your question.