GTA and Skyrim are very different games and therefore need a different approach. GTA has some key characters which drive the story. The other NPCs are ‘set dressing’: fairly simple, nothing interesting to say, don’t have a home. They are just spawned in where needed. Skyrim has a different approach. Except soldiers/guards pretty much every NPC has a ‘life’: they have daily routines, unique voice lines, a place to sleep and go there every night - except they are on a quest themselves.

GTA and Skyrim go for a different feeling, which is why they need different solutions.