Less quests, more events.
Apparently I was not clear enough :
- Less demands from npcs who usually explain why you don't have a choice, or that you can refuse for a flat loss of xp/content/whatever.
- More situations where your char/party gets entangled in, requiring action.
Here's a fix for the issue of "why would my char help npcs but why would I not as a player".
This works for me. I think the motivation thing is symptomatic of a broader problem, which is that the archetypal CRPG protagonist is an adventurer-in-search-of-adventure with no local connections or obligations. Maybe you’re the chosen one, but to any random NPC you run into you’re just a disinterested third party.
Developers sort of expect you to play as a knight-errant or, failing that, to do all the side quests for metagame reasons.
Give the player an actual job, or at least a built-in set of social obligations, and suddenly you have a reason to do shit that may not be directly connected with the main story. For example, Tyranny has a lot of flaws, but the core conceit is great: you’re not just a man on a mission, you’re a man with a very particular job in a fairly hierarchical organization. There aren’t that many side quests, but IIRC they all relate to either to your official duties as a fatebinder or your relationships with each faction (really, part of your unofficial duties as a fatebinder). And there are consequences for derilection of duty, although for the most part they come at the very end.
The origins in DA:O unlock some side quests and give you additional reasons to do other quests, although that game was also full of fetch/fedex quests.
Kingmaker—you quickly become the territorial ruler, so sorting out local problems is your business.
Piranha Bytes doesn’t start you off with a job, but they always make you get one. Start off as a useless scrub with few/no connections -> do some number of scutwork side quests for a faction so that they’ll hire you. This is also a great example of interconnected side quests: when Gothic or Elex or Risen says here are five quests, do any three of them if you want to join up and advance the main story.
This is one of many reasons I’m really looking forward to playing as a police detective in Disco Elysium. Maybe I’m a diligent cop, maybe I’m a corrupt cop, maybe I just want to impress my partner—one way or another that’s a lot of reasons to do side quests.
tl;dr I think a lot of this can be solved by giving the PC an occupation other than drifter/murderhobo, either from the start or from very early in the story.