Perhaps to more accurately reflect their role now, given they don't just control fighters.
Thread drift warning - Mr C is right, ABMs do control many varieties of air traffic now. You may notice that that sentence included the words Air, Traffic and Control. Heresy when suggested to an ABM, but since their day-to-day role on current ops is keeping aircraft
apart instead of bringing them
together, the old distinctions between the branches are more blurred than ever! At least from the end user's point of view...
(pin safely pulled; retiring)