As I recall, some of these early games even had a fountain of youth or some such you could find to reset the age of your characters. In general, though, unless we're talking huge gaps of time between games, I don't see why it should be such a factor. It isn't even a factor in many TV shows, in which the characters never seem to age at all (Simpsons comes to mind).

The more I think about it, the more age just seems like a pain in the butt and not worth messing with in a game (provided it's not part of the theme or important to the story somehow). That said, it could certainly lead to some interesting situations where you're forced to deal with the infirmities of old age--but usually any efforts to "force" players to deal with unpleasant, un-fun stuff leads to bad reviews and lack of sales.