Red Superfly
You creepy little stalker
Despite the fact the likes of Zelda, and Mario, and Smash Brothers are all brilliant and truly awesome and all, they are seen as kiddy merely for the fact that they are cartoony.
We see quality games, the modern moron sees a kids game.
Those that are young at heart still enjoy cartoons, they are a form of medium that, contrary to popular belief, are as adult as they come sometimes.
Despite the fact live action is seen as "adult" - there are a load of juvenile live action TV shows and games out there. It's merely a trend in western society to class cartoons as fantasy, which they are. The fact that they are fantastical means it relates to a time when we believed in such things, when we were kids. Our society is constantly telling us to "grow up" and do something sh*t like accounting or something. Cartoons ARE kiddy, by definition, even though that is far from the truth, it's just that people are monumentally stupid and ignorant.
Despite our lovey-dovey, PC filled world of nonsense and being "open" about going against traditions of our culture, we are a bunch of hypocrits. We are still racist, prejudiced, sexist, and we still think cartoons are for kids.