I'm very sorry to hear of your health issues due to measles. I'm also very sorry to hear of your DD's problems. I really sympathise and i know what it feels like as my DD had health issues too, including intestinal ones. In fact we are just out of hospital again.
You ask why parents dont vaccinate and i will happily answer your question. We havent vaccinated DD2 because her elder sister's health issues are due to her having reacted badly to DTP vaccines.
Our doctor doesnt want either of our children to have MMR and he is even unhappy with DD2 having single measles.
So like you, my children are not protected from measles and my eldest is immune suppressed and frail.
However i do not urge other parents to vaccinate their children in order to protect mine.
I wish you and your daughter all the best. Life is not simple.
(By the way there is a fair amount of misinformation in your blog post. It is a tricky subject to get info on. However various freedom of information requests and court hearings have happened in recent years and more info is there if you dig around)