What if you add each or at least parts of the heroes a couple of their own quests?

I had the idea that if the heroes had their own line of quests that you can complete and get certain buffs or new skills that you don’t discover in the usual way, and the hero’s story is replenished depending on the quest development options. Simply, the fact is that the stories of each of the characters are there and they are written well, yes. However, it seems to me that you can do better. Yes, I understand that this may stretch the time and you can invest a lot of energy in it, but I think it will be interesting. What do you think?