Well, they're not
ALL side quests. There's still active development being done on the main quest - the one about the Qeteshians vs the Nergalites.
Also, it's seems to me that from the very beginning it's always been implied that the MC's ultimate goal is to sleep with whatever beautiful woman crosses his path - that's his primary motivation, his driving force.
Lastly, I think you're getting too caught up in the name of the game. When he first started making the game,
Tinkerer probably just thought that "Peasant's Quest" sounded cool and was accurate enough - You know, a game about a peasant who goes on quests.
I don't think the game's title was ever meant to go as deep or mean as much as you wish for it.