Sometimes we have to suspend believability for the sake of entertainment. In this case the age of the character do not matter, similar to how these characters are able to escape death-defying situations that would normally kill a regular person.
The Western mindset is very fixated on realism this is why concepts are done differently from Japanese. This is why many time the character design that comes from Japanese artist are really imaginative. They do not get bogged down of how realistically things function.
Ageing the character to her actually real age in looks would subliminally mean that she is getting old and we have to move on.
Old snake means an end of an era.
Older Dante means giving the reins to another character
An older Jill, Claire and Rebbeca would mean the same here. It would give that audience a timeline.
Nowadays I feel that Japanese designs are moving towards a more realistic Westernised style.
Maybe it got to do with the motion capture and having the same actor for both acting and voting.
If AI tech get more advance we could see both be separated where the actor just voices and the motion is of a different person.
