I think it's a bit more than "because players put in almost no effort" but I do agree that is a big factor.

I'm probably nitpicking here, but I really hope they put a lot more thoughts into each quest. For example I remember one of the brotherhood tasks is to assassinate the Emperor, but it was a very disappointing task as far as I remember. Admittedly, removing the markers and such definitely helps a bit, but I can't help feeling that the game designers just wanted to pump as many quests into the games as possible, and call it a day. I'd rather have just half of the quests, but with each of them having more depth and require more thoughts.