User blog comment:Nord Ronnoc/Mass Effect San Diego Comic Con - What We Know So Far/@comment-7622429-20140728174616/@comment-58609-20140729084435

I don't think there's much of an excuse to not have a playable non-human unless the story is structured in a way that prevents it (e.g. the story itself of ME1 prevents the main protagonist from being an alien - first human Spectre and all that). As for the marketing standpoint, that's not really much of an issue. The game can just as easily be marketed around a human (game cover, trailers, ads) but feature non-human players. 'Dragon Age' marketing always used a male human for the player character, but featured non-humans from the outset.

Then again, Ubisoft has shown how 'difficult' it is to have female human characters in a game so what would I know? ;)