Deerling, I do not vaccinate my chicks, either. The chicks I have ordered from hatcheries are not vaccinated (that is, I do not purchase that option).
The Merek's vaccination, actually, prevents the disease from forming A LOT of the cancerous tumors in that variation. A bird can contract Merek's even having been vaccinated, but won't necessarily develop the tumors.
Many affected birds often recover, depending on which way the disease progresses, for lack of a better term.
Some horror stories are truly heartbreaking, when whole flocks are devastated, owners have the soil removed, etc.
But if you were to ask every BYCer with chickens (yah, there are some with none - I know!) if they have their chicks vaccinated, the huge majority would say no. And that's with BYCers, remember, who are probably more responsible than some other folks who have chickens.
Now, if you're breeding chickens for sale...... In a big way.... Well, hmmmmm.
I would still buy stock from a non-vaccinated flock. That's just me, though.
But I didn't want you to feel like you weren't doing "everything" for your flock's health by not having your chicks vaccinated.