I've long said that Bioware needs to get more weird and "alien" when designing species of the MEU. I'm really tired of every crew member being a bipedal humanoid. However, after ME3 I found myself missing the hell outta shooting at the different species we've come to know, instead of their Reaperized husk equivalents. Sniping human space pirates on some backwater rock, seeing the pink mist erupt from an Asari mercs tentacled dome, or putting down some twisted Salarian organ smuggler....I need some more of that.
And with the Ark initiative being such a seemingly massive endeavor, it's quite possible there could be splinter groups that oppose our own approach to things. It'd be damn boring if every single soul on the Ark was on the same exact page.