Because the goal is to move the ball down the field in units measured in yards, which is part of the greatest measuring system in the world, the Imperial unit system that includes feet.
So I guess for people like you living in that indiscernible blob of continents and islands known as "Not America" it would be called Meterball. Oh wait, I forgot you're all illitarite commies so you'd probably spell it "Metreball" or something gay like that.