So vaccinations are a weird thing. The thing about chicken vaccinations, is that most don't prevent your birds from catching the disease they only prevent the symptoms, and they're only about 90% effective. (This is especially true of the Mareks vaccine which drops in effectiveness a small amount yearly.)
Which means that if your birds catch something, you'll never know it, they might get other birds sick, and you might loose some of yours anyhow. But the rest will live happy long lives, shedding potentially large amounts of pathogens.
Now if these are dearly beloved (and isolated!) pets with good biosecurity, that might be worth it for you. You guarantee that at least some of your beloved babies live even if they get sick, AND you take substantial measures to make sure they don't infect other people's birds, this may be a legitimate option for you.
For me, I would always rather know if my birds are sick or not. I would rather burn my whole coop to the ground, wait 2 years, then start again, or breed for resistance, if something that bad got into my soil and flock. If these are beloved pets, this kind of mass culling might not be a good option for you, but if you want eggs or food this might be a reasonable way to manage your flock.
(As an aside, most human vaccines do NOT work this way, they actually kill the pathogen in the body. Most chicken vaccines do not kill the pathogen, only prevent symptoms.)
So this is a personal choice based solely on how you value your animals, how you view disease resistance, the individual vaccine, and why you want your birds.