Usually I just want to explore the developer's creation. For me, a main quest is a hook to help describe the environment and give context, but I'm rarely bothered that much about it; particularly as many main quests are not particularly good.
I'm definitely a side-quest-and-sandbox sort of person, in keeping with the original ideas behind tabletop DnD. I am less keen on very linear games, with overly cinematic presentation, and rarely like to be forced into action against my will.
