[T-nex]

My guess to the answer is to make it extremely inconvenient for people not to be vaccinated(as oanst suggested too). Also to educate people on social responsibility. There's nothing worse than seeing a guy with a flu in public(ok maybe a few things but still). I mean fuck him if he wants to risk his own health. but the flu is potentially deadly, and going out in public when sick, you could potentially kill others by spreading the disease.
But that has nothing to do with vaccines. It's to do with being a sensible person.

At least that's my take on the whole thing.