Oddly enough, my parents' fears weren't targeted at the cartoon (no more than any other cartoon we watched) or even really at the game. Their fear was that Satanists were using the game to meet children, and my my friends and I might somehow accidentally run into some and get kidnapped and ritually sacrificed.
I don't think that's all that odd. Role playing games were rather new and wasn't something your parents were likely to have experienced when they were teenagers. Whereas people had been watching cartoons for the last 50-60 years and most parents weren't concerned it'd turn their kids into raving lunatics. And, yeah, it's hard to believe so many people took the the whole kidnapping and Satanic ritual belief of children seriously.