It was called that until you and others told them that was too confusing.
In fairness, I think "First Four" is a stupid name. It's obviously intended to be a cutesy play on "Final Four," but the latter name refers to the fact that four teams make it to that stage of the tournament. The "Four" in "First Four" refers to the number of games played in that round—four games, which by definition means eight teams. I guess they weren't able to think of some sort of alliterative or rhyming nickname that went with "eight."
