Mostly, I think light management acts as a proxy for time management. If you have to rely on torches to see, and they only last so long, and you can only carry so many of them, then there is always a source of time pressure, even when there aren’t wandering monsters to worry about. And I do think time management is a very important element of dungeon crawling. Time pressure gives weight to every action, and creates meaningful tradeoffs between expediency and caution; things that aren’t as relevant in the context of a game like Zelda where you’re much more constrained in how you can interact with the world and deal with challenges. Link doesn’t have the option to pick a lock or break down a door in a dungeon, so the player doesn’t have to weigh the costs and benefits of taking the time to find a key, or making noise battering the door, or breaking one of a limited number of picks. Zelda also has the benefit of being played in real time. Players usually don’t go around checking every wall for hidden bombable spots because doing so takes time and would get boring, but in D&D everything happens at the speed of narration. Unless time is a limited resource, there’s no reason not to scour every inch of every dungeon for secrets and traps. Light management is an easy way to create a reason not to do that.