There is literally no such thing as plate without padding outside of Hollywood.
You are making a postapoc game, and player finds an old style damaged infantry helmet (a metal bucket basically). Since it's better than nothing, he equips it. Then he gets hit by some blade, or bullet, or a raider tries to bash their head with a stick.
And by the way, padding also varies in quality and design. There is thin padding, and there are very thick padded armors. You can pad the insides of it with cloth or even animal hair afaik. Can be just cloth or well tailored gambeson. But then gambeson can be as low as your knees, or short. A hit in the upper part of leg can meet nothing, or up to say 4 layers of armor (cloth, plate, with padding, and chain over padding on top of it), in different variations.
And then there are other settings than muh medieval europ.
Not everyone in all history was ideally equipped by the guide from the book (including historically correct shoes and ornaments on clothing) or with a personal servant; and neither players would be in the game.
In reality of RPGs though, itemization people loved never was about ac or damage thresholds or any hemafagotry, but about narrative and rarity and unique effects of items, and if players felt they earned to own them; and the element of larping and dressing up of course. Full Plate in BG1 is just banal AC; it still felt like Full Plate due to power level and cost, rarity, weight and strength requirement to wear.