I think the biggest thing about races (and why I can at least partially excuse them for their kind of pathetic list of available races at this point) is that they *have to* be able to speak unbroken galactic basic because of the voice acting. This means no Wookies because they physically cannot speak galactic basic. This means most of the other slightly more alien races are out because their galactic basic is so broken (if they can speak it) that it would just be jarring to have them speaking like the other races do. There are some races, however, that would make sense for them to add...my personal choice would be either Mon Cal (not sure if their galactic basic is clear enough though) or Bothans