I will play the devil advocate here. I saw a few peoples mentioned that the NPCs wear much better looking outfit. It a lot easier to create a relatively static NPC with is personal outfit than to create one that adapt itself for player characters that come in all sort of shapes.
What's even easier IMO is just designing tons of options for player characters and use all those for the NPCs. The devs wouldn't have to build any NPCs from the ground up then. They could just mess around in character creation like the rest of us do.