ME2 didn't really have a story, it was purely about gathering a bunch of psychologically stunted (but bad-ass) companions, fixing their personal issues by clicking through ten dialogue options and defeat the bad guys in ten minutes.
For ME3 I sincerely hope BioWare will include a bad ending where certain past renegade choices lead to either a Reaper victory, or a universe where the Illusive Man install himself as God-Emperor using the technology from the Collector base.