Consider this: Elder Scrolls titles have had development periods anywhere up to 6 years. That length is important, as it allows the extra time to put a great deal of details into the game, from alchemical plants and trees and rocks, to kitchen clutter, to a variety of weaponry and armor. The greater the variety of all of these, the more believable the world. Some, like the weapons, are critical to a satisfactory gameplay, especially in a game of grand scope. Others, like the various foods and utensils, are important for roleplay, which a significant subset of TES players desire.
In recent years games are, in my opinion, approaching a certain level of visual saturation. Models have become more detailed and have higher poly counts than before, but further improvements in their smoothness and complexity may well be lost in the fast-paced games we play. Textures trail behind slightly, but are nearing photorealism in some games - and any improvements beyond photorealism are pointless. In other words, the 'stuff' developers are putting into their games will look 'good enough' assuming they are skilled at the task.
I believe it is eminently possible for Bethesda, rather than making all their items brand new each game, to create a library of in-game objects (likely at slightly higher detail than is feasible with current hardware, as a future-proofing) and pick and choose from it (reducing detail as needed) for each successive game. It would allow for a much greater emphasis on actually building the world, the characters, and the quests.
Personal tastes will no doubt differ - Glass armor in Oblivion, for instance, garnered a widespread loathing. I can think of very few who would like to see it recycled. Bethesda could always pick and choose select items to update for the next title, while keeping others. Or update and keep at the same time, in order to add a degree of variety.
Though I would be quite satisfied wearing the same old suit of Mithril, myself.