As long as they are being rendered in real-time, I'm fine with including them. Usually they don't include the highest implementation because the camera is pulled back far enough that you wouldn't see it anyway, so there is no point in stressing the system on unnecessary rendering techniques. It's still a balancing game, but you know that, lol.
There is still a lot of detail if you can wedge the camera in close enough during game-play. There is also the effect of scene lighting. Cut-scenes are lit very specifically to show off the detail in the materials. It isn't done this way in game-play because you can't direct the camera to only look from specific angles, obviously. Unless, of course you have different lights set to only affect certain objects, but then the scene doesn't coalesce. You know this too, I'm sure, but I'm merely pointing it out for others who may be reading the comment.
One of the things I really like that AC:Unity does, is it goes straight from cut-scene to game-play, and you can actually see it switching from scene lighting to game-play. I enjoy that for some reason.