Simpsons Rule

I'll be closing down the Best Animated Sitcom poll later today, which the Simpson's won in dominant fashion. It is not surprising the Simpsons won, the show has been blessed with excellent writers throughout it's existence. However, I have always wondered, why no one on the show has ever aged, similarly, why does Goofy get to wear pants and Pluto is sans trousers? Tonight is the last game for the Rusty Kuntz's (we still have not won, but will get them next season), but I will be unable to participate. I have had to spend more time studying for the BAR and still maintain some semblance of a boxing training schedule.