I happened to catch an episode or two when I was in 1st grade and thought it was weird that there was a cartoon version of Star Trek. But they replaced it with Robotech a month later and I basically forgot about it until my son found it on Netflix a year or two ago.For which Prime fans, though?
I suspect the overwhelming majority are like me - watched a couple of the animated episodes back in 1973 (or in whatever year they first came to it) and weren't engaged sufficiently to stay around to see the rest.
I wasn't even born yet when TAS came out.