Basically, it all comes down to relatability. Freed says:
“You know, the reason for our humanoid range of species, it’s a matter of relatability to a large degree. The further you get from human the more difficult it is for players to get into their mindset, the more difficult it is for all the other characters in the game to relate to them the same way. There are enormous technical obstacles, there is building all the lip synching, all the emotion into the face of the human is incredibly difficult and time consuming, doing that for something like a Wookiee – and we couldn’t half do it, we couldn’t let Wookiees be only a third as expressive as humans. At that point we’re just giving up.”
Freed explains in the affecting their overall view on the game itself as well.
Freed says:
“It’s not the aesthetic of it, it’s the whole package. It’s being the barbarian from some planet who is stronger and wilder than everyone else and who is only half understood. That’s what people love about Wookiees. We don’t have anything against that storytelling, it’s not a moral opposition to not having inhuman characters but in order to do it right you need to write a story around that character.”