Quite easy to answer - when they figured out they could get people to buy yearly sports titles with little to no improvement. EA spent much of the 5th and 6th generations as an also-ran, pumping out mainly movie and sports games and generally being easy to ignore, except when they cockblocked Sega's NFL2K series and bought out a bunch of smaller PC developers to harvest IP.
John Ricietello(SP?) came along and, for a VERY short period of time, actually turned EA into a company people might give a shit about, with Mirror's Edge, Burnout Paradise and Dead Space. Almost immediately after DS did well, EA turned into outright cockbags with "project $10 dollar," the failed attempt to turn Battlefield into a CoD killer, and another spate of buyouts (how's Pandemic doing?). I think the ousting of Ricietello by the board (and make no mistake, he was ousted) is partly because EA would rather go back to that comfortable period where sports fans bought blindly and actual gamers ignored them. It was an easy, profitable time for them.
Honestly, I kinda wish them the best in that. The sooner I can just ignore EA completely, the better off I'll feel.