I believe you are judging this in a wrong way. If say you watch 10 crappy Hollywood movies, that doesn't mean every movie that comes out of Hollywood is crap.
It's the same with Anime. A turn off for older people is that they probably watch shows which are targeted for 16 and under audiences and see the big breasts and the too cool, and super powered characters and assume everything is like that.
not all anime is like that though. Shows like Monster, Gungrave and Death Note are targeted towards 17 and older, not because they are sexual in nature, but rather because the scenarios, themes, and story are things that a mature viewer would love, while a 10 year old kid would deem boring or confusing.