In the launch version of Final Fantasy XIV, there were a number of currency items that dropped from tribal enemies like the Amalj’aa and the Sylphs with the vague implication that these currencies would be useful later. This did not happen. I still have them in my inventory, though. As it has been a very long time since basically anyone had thought about the Amalj’aa as active content to get through, especially as some kind of dangerous stronghold to infiltrate, the odds of these items ever being useful is vanishingly small.
However… I still keep the items in the inventory on the off chance.
This is, not to put too fine a point on it, very silly. But I persist for whatever reason, just like I still have some items in my bank in World of Warcraft that will never be needed ever like cloth items on mail characters. (Not ones I would ever wear for RP purposes, just ones that look cool.) Sometimes we just store things that are unlikely to ever have a purpose beyond having a thing. So do you have MMO items in your inventory that are never going to be useful? If so, why?