If you use two different types of armor or want to save a piece of armor with a trait you don't know until later you naturally don't want to deconstruct that item, and it would be nice to "hide" it from the deconstruct tab. At the moment you can mark an item as junk or put it in the bank, but you will still be able to deconstruct it, so if you are a bit to fast you will destroy an important item. My proposed idea is to implement a "mark as important" and you will not be able to deconstruct those items, or research them or anything of that sort. If you wanted to deconstruct or research you would naturally chose to "lo longer mark as important"
tl;dr: "mark as important" so that it cant be used in crafting of any sorts.