To answer the origin question: I don't care, I wouldn't buy it for PC anyway. I'm against Origin, but it's kind of moot since they can't install it to the platform I'd use.
To answer the title question of Mass Effect 3: Yea or nay, they lost me somewhere partway through ME2 and I have no vested interest in the series anymore. Which, in the end, makes it even harder to care about Origin.
The fanboys, even a good chunk of the ones hemming and hawing will buy this game, and a ton will buy it on PC despite Origin and their own objections. They will further validate the notion that this is okay, because self control is almost unheard of in the gaming community.
This is assuming any truth to the assertion that PC copies will use Origin.