The only thing I can think of is that they want 'EA Sports' as the main brand opening the way for other sports 'EA Sports Tennis' or whatever. But 'FC' really? What's that?
The move is actually an excellent one, because FIFA is a corrupt organisation whose main purpose is to syphon funds out of clubs, fans, and countries into the pockets of their morally bankrupt leadership.
EA should've done this years ago.
The suffix FC is used by teams on both sides of the Atlantic, and should be well understood by fans of the sport.
Calling it 'football' might confuse some fans of American football, but I really doubt any American fans of 'soccer' will be confused, let alone excluded.
Cover art alone is enough to indicate the game being played. There won't ever be person with a helmet on the cover of a soccer game.