I have a theory about that grey trash that make it critical to the game.... I think it's used to create a player's 'luck' - so a player needs to collect "x" amount of trash items before a rare (or uncollected) item will drop. Simply put ... it's a counter. It's similar to the way lockboxes drop every 6 hours of 'time in game'. However, the difference being that the trash actually gauges that you are playing the game and running the content. When you have collected enough trash, you get a rare drop or a drop that is currently 'uncollected' by you.
My theory is simple: it was the original intention of gray trash drops to be used for player income. My memories of early days DCUO bring with it the tightness for cash back then. It's only the money glitches that brought about cash difficulties, and if these had never occurred, cash would still be rather tight. Sure, these would only provide small amounts, but couple that with cash drops that we get through instances, broker sales, and other items sold to vendors, it's enough to survive (unless you're super careless and need to repair constantly). They're simply another mechanic/item that originally had intention that has been left by the wayside for one reason or another. In my opinion.
