No one here is going to be able to give you a definitive "why." People can surmise, sure, but it's public perception, which is often something that differs for every individual, and so there isn't one single answer to give.
There's nothing "we" can do, really. Public perception is an impossible beast to tame. You could put up billboards, run ads, hand out flyers and you wouldn't be able to change much.
But you know what? It doesn't matter. Of all the terrible, stereotypical misconceptions the public and society at large accept as truth, this really isn't one of them. It's cartoons. Usually if cartoons and questions of society as a whole cross paths, it's someone overreacting or reading too much in to something. Watch what you watch, enjoy what you enjoy, and if someone questions it, explain it to them. End of story.