I think it's harder to understand the point of view of parents if you aren't a parent yourself. Parenting is a hard job and I never realised how hard it was and how many sacrifices you have to make, until I had kids myself. Having spent so many years of your own life bringing up another person it must be heartbreaking to see them move so far away.
However, once children have grown into adults, parents must let them go and let them lead their own lives. Some parents can't do this and try to live their lives through their children and grandchildren, putting incredible pressure on them. For some parents it might seem as if you are rejecting your whole past, family, friends and way of life as not good enough, and I can see how they could get upset.
A good parent will support their children whatever, even if the decision hurts them. Make the most of your parents - it is easy to take them for granted. I lost my Mum to cancer 6 years ago and I would love to be able to have a Mum to talk to again.