Both LP and FP were requested as conditions in the loot filter a couple of times and Mike, one of their Senior Devs, did comment on this a while back.
Continuing the discussion from Please add legendary potential to loot filter ruleset:
Not sure if their stance changed by now.
But I totally agree with him.
Up to a certain point yes, but the more you allow the more precise it gets the more kinda “automated” it will be where its a no-brainer to pick up loot and you will interact with loot a lot less.
I really like that nerve-wrecking feeling when a base type drops with some good prefixes or suffixes (you can see that already in the items name) and then you wanted to “check” the item when hovering over it and eitehr get disappointed or blown away.