this is a cost effectiveness issue and an aesthetic vision issue. developing both modes, especially in this level of detail take time, developers have deadlines, sometimes down to individual. they cannot dawdle. because many of the actions, the combat, cooking, etc are very 1st person centric in this game, they will have to put all their efforts making that look good.
so they chose to focus on something rarely done before, and do it very well, and that means sacrificing doing something in parallel to avoid having both features suffer in quality.