In most fiction, characters never age and and time hardy, if ever, moves. I believe this is because makings some changes can complicate things for the creators, as well as alienate their audence. But still, there are some things that should never change(namely icons), but are their series that you think should move forward and adapt?
Take Family Guy, for instance. Sure, all the other characters age and mature, but why does Stewie remain one? Would aging him to two cause some problems?
And this is probably one of the reasons why most people prefer the Digimon anime over the Pokemon anime. Even in the Pokemon Adventures Manga, the characters age. Of course, the video games were no better.
They don't even look 10.