There aren't generic Krogan, Asari, Salarian and a number of other species husks I would assume because Bioware just didn't want to have so many enemies that fill similar jobs as each other.
They had to take out holstering your weapon so they could get more memory for other things, and seemingly filled two DVDs to the brim for the 360 version, they probably just didn't have the room either way for a ton more enemies of different types and races.
Then there's the fact that they cut a bunch of things, took out a squad mate and only finalised an ending by Novemeber, so they probably didn't have the time and man power to get any more done.
They had to take out holstering your weapon so they could get more memory for other things, and seemingly filled two DVDs to the brim for the 360 version, they probably just didn't have the room either way for a ton more enemies of different types and races.
Then there's the fact that they cut a bunch of things, took out a squad mate and only finalised an ending by Novemeber, so they probably didn't have the time and man power to get any more done.