I'm guessing the game didn't launch with the "/team loot alpha" feature? But it was added later to solve team loot problems and admitedly the game probably didn't need much more until the recent game focus change to big boss type mobs.
The loot messages were probably always an idea they liked, but there was never really a need to implement it: "/team loot" was enough for your stock old style missions even if it didn't cover the chests.
But if they start adding more static spawn drops or big boss style drops, which is where the game looks like it's going, then they're going to want to up the priority on the looting messages.