There are items we other players like to use PoF on you know.
Sure, disposable items (imbued), less people care about these because they're very easily replaced, they're useful, but if you dedicate the time and effort to farming a clean legendary, it should last as long as you want it to or until you find something better. Otherwise, what's the point in making "clean items" so rare? What the hell is the point in farming for clean legendaries when you can get 100+ brittle legendaries with better mod quantity & intensity than the one clean legendary you may or may not even find?
Go get a Clean Major/Legendary Ring or Bracelet, build a suit around it, when it gets low on durability how pissed would you be when you find out they can't be Pof'd?
"Oh, so 'clean' means different things based on what type of item it is?... Gotcha...." - Inconsistencies kill the game for people no matter what aspect of it they're associated with. - Fix it.
These items should have a tag like Brittle or Imbued (something that prevents PoF) Or they should to be PoF-able.