What about (not so) new players being practically shut away from all higher kingdom positions because hundred year old kings and dukes just sit on their asses in their capitals forever?
Aging penalties at least could make gameplay unsatisfying enough for such players to shelf their ancient characters. Otherwise there will be just characters who win the game because they were created ten years ago and accumulated stupid amounts of gold, honour, influence, stats, etc. without any drawbacks.
The problem with that is twofold.
First, there's not a particularly high correlation between "characters with high physical age" and "characters we want to remove from their positions so someone else can take over." It's not, after all, like there's anything specific about a
character who's been around a long time that makes them inherently less good for the game, or less worthy to hold a high position. It's characters who hold high positions purely for the sake of it that are really detrimental.
Second, age doesn't actually have a strong enough turnover effect. Sure, I've seen a half-dozen people grump that their character is getting old, and they have to delete them...but I've seen a
lot more just keep the character out of battles, sitting around in their towers doing nothing. Indeed, I would posit that it is exactly the type of person we want to affect most that is most likely to start from the assumption, "My character gets to stay around," and work from there on how to make it happen.
That's why we've come up with the Health mechanic. It is essentially the inverse of Age, for while avoiding Age and its consequences means staying at home and doing nothing (thus making you much less likely to lose your position), avoiding Ill Health and its similar consequences means getting out in the field and doing stuff. This not only means that your characters are more likely to be interesting, it means that they're more likely to run into situations that cost them their high positions.