Pick any classic from the golden age of gaming and you'll see a shitload of unnecessary details. Did the games need those? No, but the devs implemented them anyway because they cared!
Even when technology wasn't quite there yet to have physics and all that stuff, developers cared about making the world interesting and reactive.
Games like Morrowind and Gothic didn't have physics, but they let you pick up clutter, and you would provoke guards if you picked up things that belonged to others.
Ultima VII also let you pick up and move everything, and NPCs had schedules, and you could BAKE BREAD because why the fuck not? Was there any gameplay reason for baking bread? No, but you COULD because it is COOL! And it wasn't a stupid abstract crafting screen like we get now, but you put FLOUR into WATER to get DOUGH which you put in the OVEN which creates BREAD. And baker NPCs would do this as their job schedule. Was it needed? No, but it's great and people still remember the game for this reason.
Fucking adventure games in the 1980s took care to give you feedback for trying things on background items. If there's a rock in the scenery and you try to pick it up the game says "This rock is too heavy to lift." Yeah, it's not a system, it's just specifically hand-written descriptions for every impossible action, but the developers CARED! They could as well have written "You cannot do this." (which some adventure games, particularly later ones, do, showing a lack of effort compared to the earlier games that have unique responses) but they paid attention to add little details that enhance the experience.
FPS games, particularly the Build Engine games, added lots of little environment details to make clutter and even some wall textures react to being shot, like a computer screen texture turning into a broken screen and throwing sparks when shot. Was it necessary for gameplay? No, but it enhanced the atmosphere and the feeling of being in a world that reacts to your input.