I'm brainstorming a campaign and I've been thumbing through the various career books in my SWRPG library. When I come to the playable species sections, I find myself reading the entries and thinking, "These are great! Too bad none of my players will ever want to play any of these."
I'm probably revealing too much of the psychology of my play group but I've noticed that players often drift to either Human (or it's Corellian/Mandalorian alternatives) or one of the "sexier" aliens: Chiss, Twi'lek, or Falleen. Of the six campaigns I've run, I can't recall a single oddball alien like a Gand or Iktochi, let alone a stock Star Wars character like a Wookiee. The last time I was actually a player in a Star Wars game (Saga Edition, I think), I wanted to play an Ewok but my GM (who sucked) wanted to do a "hard space warriors being hard in space" campaign and wouldn't let me.
I'm starting to pay more credence to the theory that most (not all, but most) players want to play themselves but smarter and better looking.