It didn't make much sense to me at first along with the presence of books that are way younger than the Dragon Wars, but then you learn that the Draugr didn't die so much as slowly waste away over the centuries as they transferred their life essence to the dragon priests. It's kinda weird to include libraries, kitchens, chairs, tables and dining rooms for corpses unless they weren't entirely dead when they were put there.
I've thought another reason, it's the will of the legendary immortal hero. Since in all the game it's hinted through dialogue and various lore and references primarily in Before the Ages of Man last sentence. And in a way you are considered the immortal legendary hero, thus strange phenomenons always follow you, strange events always following you, traps resetting, food that were rotten coming becoming fresh the day they were stored, etc.