Don't forget Baudolino that those original fans of the hardcore games are 20 years older now with more responsibilities, and less free time.
Sometimes people don't have a lot of time to play, and they can put the game down for long stretches and forget where they left off when they pick it back up. I often find myself playing a game for a month, then moving on to the newest shiny thing. I don't always remember where I left off when I get back to the first game.
While I didn't have problems remembering what to do in D:OS 1, it's not a bad idea for Larian to remember that not everyone will play through the entire game in a few weeks. That's especially important for co-op when the difficulties of coordinating schedules means that it might end up being only one playing session every one or two weeks.
I'm not against the idea of a quest log that organizes efficiently the info you get through exploration and dialogues, Stabbey. I'm definitely against the idea of a quest log that solves the quests for you, which is basically what you get when you play a run-of-the-mill RPG these days.