Well I think it's part of the Fifa licence deal to make at least a single Fifa port for every major platform. That's why EA's philosophy is to bring Fifa asap on the market for every system. Doesn't matter if it's Switch, Wii U or PS Vita. And if those low effort ports already sell well enough, they have aquired new sales grounds and if not, they at least can say they tried to support these platforms.

Because football is the worlds most popular sport maybe.

Because they don't have any other sports games that are nearly as big. Even outside of Europe, Fifa 18 and Madden 18 sold equally well (each 2.9 million on PS4).

Seems abit obvious really, its the biggest selling sports franchise, and is an absolute system seller in most european countries.

It has greater appeal globally and likely is safer bet to turn a profit than NHL or NFL game.

The answer is obvious:

FIFA 18 Sales: 15.8 million
Madden 18 Sales: 4.4 million
NBA Live 18 Sales: 0.4 million
NHL 18 Sales: 0.9 million

They always do FIFA first because FIFA is the most likely to be profitable.

FIFA certainly makes more money than the rest of the EA sports games combined.