Because EA woke up one day and remembered they owned BioWare, so now we're operating under Electronic Arts SOP until they start developing the next Madden game.
Seriously, though, I don't think they're going to. Same-sex relationships has always been seen in M-rated games and this is a T-game. And since LucasArts has this thing with catering to the younger generations, we won't see same-sex stuff for a while, if ever. I don't know why people keep bringing it up. If it happens, it happens. If not, so what? Sure, it's make the game more fun, but so would playable Trandoshans or removing EA's pull over the game, and we're not getting those soon either.
I agree with the first part of your statement about EA. That wouldn't surprise me in the least. I've kinda made it a hobby to watch EA and their shady business practices. lol
As for the second part, The ESRB doesn't differentiate between OGRs and SGRs when determining the rating. Both KotOR and KotOR II had SGRs, though not as fleshed out as those in Jade Empire, Mass Effect, and the Dragon Age games. Juhani declares her love for the female Revan in KotOR, but with no follow-up, unfortunately. Also, Luxa flirts openly with the female Exile in KotOR II. Also with no follow-through.
While coincidence is with you that the M-Rated games had the full-fledged SGRs, they also had much more violence, adult situations, nudity, and profanity. That is what the ESRB looks at when rating a game.