Mass Effect didn’t have non-humanoid aliens because it would’ve been costly
There were quite a few alien races represented in the Mass Effect trilogy. Although they may have scales, blue skin, or might even look like roaches, they were basically humans with a palette swap. That’s disturbing, but considering how limited consoles were during this generation, that may have been a necessary step.
Apparently, BioWare thought the same, too, for they considered having non-humanoid squadmates in the games, but they discovered that it would have taken away from the rest of the game.
All the party members in the games were based on the humanoid skeleton because the development effort for non-humanoid playable aliens would have been great. Instead, the studio pushed to make a “larger, more polished game.” Also, all squadmates had to function like human characters in the sense that they’d have to be able to carry guns.
Honestly, I’d love to see the galaxy’s first Hanar spectre in the next Mass Effect game. Now, that would be freaking amazing! Also, I think next-gen consoles have more power and RAM that can be dedicated to render more than one type of “skeleton” in games.