1.aging: the age on characters should infect them if a human is at the age of i child in rl it should be a child, and if you are old it would have been fun if you got grey hair and died.
2.armor: a fullplate isn't a fullplate, it has to be iron steel bronze and so on, leather should be cowleather bearleather and so on. and if you find a plate on an orc you have to go to i smith with it to make it fit you for example.
3.crafting:then it would be much fun to craft the things that you need, and make food since its going to be a food system.
4. NPC: in cities alot of ncps LOT of them walking around and maybe have a purpose go to the bar or something.
5. cities: big houses in nwn the houses are to small.
maybe ill come up with some more ideas later.
if the is a topic with all that already please link me
6. btw this is way out of D&D but it would be fun to have more that one xp "ladder" and several ways to get xp like hunt you get hunting xp.
Do you think is that too much ? I would think so, because making differences between types of leather or making fit an armor for you seems exaggerated.