smallpox was not entirely eradicated by vaccination. in fact, it was only after the vaccination programme was reduced, and other measures were used alongside (such as better sanitation and isolation) that smallpox was eradicated. vaccination was not the sole cause, and would not have eradicated it alone.
there is an awful lot of scaremongering that happens wrt childhood diseases and vaccines. dd1 had the unfortunate timing of coming down with chicken pox while on holiday in America. now that was interesting, as it is all but notifiable over there, and we were very nearly slapped into isolation as a result (she had a mild case, btw) - that is once the doctors had actually worked out what was wrong 
(I new what it was we were there to get a fit to fly letter, which I had to dictate to the doctor, as she did not know how long dd1 shoudl be out of circulaiton for, or when she would be ok to fly. which ws a bit worrying really, as surely you go to the doctor's to get advice, not give it?)
FWIW, dd1 had her initial mmr (as well as all baby jabs plus a whole host of others, as we lived abroad when she was born). it didn't cause her autism, but it didn't do her any good either (serious gut issues started post mmr). she has not had her booster, nor will she have it (or any other vaccination)
dd2 is unvaccinated, and will remain that way for the forseeable future.
OP, all you can do is research it, and come to a conclusion that suits your family. no on here can tell you what to do. you have to be comfortable with your decision either way.
for some background reading on th matter, search beachcomber's posts on vaccination, or bubbleymummy/bumbleymummy. they have posted a lot of interesting links over the past few years.