It also dampens what is, IMO, a very important aspect of single player RPGs: the social aspect of playthroughs being relatively unique, generating the opportunity to discuss those wrinkles and differences with other players.

Yeah, I thought about this when I finished the game as well. I wouldn't say it was a complaint, necessarily, but I did feel like it took a bit of the texture out of the game that I was able to do everything without really trying.