Keep in mind light is tied to stealth. Diminishing lighting, could influence stealth breaking Larian’s existing design. Of course, day and night cycle would be welcome with dynamic stealth systems, but those will be harder to pull of the more detailed the systems are. (I generally find that “it’s dark! All gain plus 2on stealth rolls!” works better then trying to redesign handcrafted scenarios).
The effect you suggest could be simply cosmetic, but I think it would be more confusing then helpful - like if it’s only role is to indicate your party members getting tired, it’s an unintuitive overkill which might help to transition between broad daylight to camp, but it would be odd if it didn’t interact with other systems (NPC schedules, visibility, monster presence etc.)
