Not all cartoons are for kids.
Bravo have the adult Swim series which shows programs like sealab and the Venture bros.
Also if you look at cartoons from the past 10-15 years, some of the best cartoons have been shown that are more adult orientated, but can also be watched by kids.
Take for example the Batman animated adventuresfrom the 90's.
most people who watched this show were adults.
it showed a batman in a dark tone like the burton movies.
it looked and felt as if it was aimed for adults, but kids could enjoy it as well.
The justice league as well although a cartoon started to get a bit more darker in tone dealing with violence and betrayal, and in one episode superman lobotomises a villain.
not exactly the sort of thing you want to explain to a kid.
so in this case i would have to say anyone can enjoy cartoons