It's a business decision nothing more, nothing less.
I guess its not profitable for them to support nintendo.
Looking at the madden sales on nintendo, I would agree with them.
Evidently EA doesn't agree with themselves, because they continued publishing Madden and FIFA on Wii through the 2013 editions, despite it being a dead system by then. And surely made some kind of profit, since FIFA 2013 was literally just a reskin of the previous Wii version, and still sold almost half a million copies.