ME3 is now available on Steam

Question: who would do this moments before releasing a supposed remaster, and why?

The remaster hasn't been confirmed yet, its all from information from unnamed sources and it seems to be only a couple of places talking about it.  So it could be a lot of incorrect information abound and it could be something like a remaster of Mass Effect 1 only or even on a related note the games being released on Steam.

Why bother though if it still runs through Origin? Can't you already launch non-Steam games through Steam?

it does seem to be rather confusing, if anything can have a negative impact on the remaster's takeup and profits, especially if the rumours are indeed true and they are to drop later this year. i can only speculate of Mass Effect caught as a collateral for the largerEA campaign to offer their titles via Steam. there's a bunch other EA titles and franchises ported recently and offered at decent discounts too. or maybe remasters are to be delayed, or not to be at all, and this seems to be an opportunity for an easy cashgrab

Po-tay-to, Po-tah-to 

Steam's aggressive marketing and their larger pop? Also, availability. For instance, the complete ME3 DLC pack is offered at the moment at a decent discount, something people were asksing (and still are) quite a lot and one can get in virtually one click

... quite a lot of negative feedback at the mo, orgygin's overlay is causing performance issue and doesn't seem to be an easy way to disable it for Steam users. hopefully there's a fix, or better more native Steam integration. wishful thinkgin i know