Quick question: Your grandparents didn't take vaccines because they hadn't access to them or because a well thought practice of just not taking them? Their is a difference about not taking them because they couldn't reach you and another thing is to purposely do not take them.
All of the above arguments are fair, like proper diet, exercise, clean air, but what will you do if all of the sudden you contracted a disease that you could have been inoculated for?
What if simply put you are bitten by a dog? And he has rabbies? Or you cut yourself in a metal object and you have contracted tetanus?
All of those could be avoided, or maybe if you by rare chance caught tuberculosis? The world is filled with people who don't have the luxury of clean air, proper diet, healthy work conditions and protective gear. To deny them access to vaccines or to say the solution is just hope for the best is a thought out of this world.