User blog comment:Arbington/New ME4 Teaser Pics, Possible Upcoming Reveal/@comment-9753034-20131108173914/@comment-24174486-20131109033304

"(And I'll be honest, I was somewhat surprised when the game was announced less than a year after ME2)"

I don't see why you would be. I mean, it's not like ME2 made it obvious that the story isn't over or anything. Announcing a third game in the series would have be akin to saying, "No, we're not going to leave this story completely hanging."

Comparing development times isn't really a strong argument when you consider that ME3 is an upgraded and refined version of ME2's engine, compared to ME2 being a radically different engine than ME1.