That's not the point. They exist, whether as a protagonist/antagonist or just as support characters. They have made many appearances throughout the EU, more than enough to get them noticed. This is a story-driven game, not just go-out-and-troll-the-mobs. The Chiss play an important role in Star Wars lore and history, specifically as intelligence agents for the True Sith empire. Without the Chiss, the Empire may have been devastated during the war. Therefore it is only right to pay homage to them and make them a playable race, not to mention that they were Imperial Intelligence's best of the best.
And to the OP, your ignorance and self-righteousness is disgusting. Each one of those races is an established part of Star Wars lore; many of them play important roles. Sith Purebloods (a.k.a. Red Sith, True Sith, etc.) are the basis for the entire existence of the Sith Order. Marka Ragnos, Naga Sadow, Ludo Kressh; without them there would be no Sith as we know them. Rattataki (a.k.a. the race of Asajj Ventress before her change) have influenced the realm of bounty hunters for centuries, and have sent powerful contenders through the Great Hunt. Not to mention the repercussions of the work of Asajj Ventress (without which the Clone Wars may have been completely one-sided, the Bando Gora cult may still be around, and Count Dooku would have had less influence on galactic events). Without Miriluka Jerec would never have existed, and the Valley of the Jedi would still be an unknown. Without Mirialans Barriss Offee and Luminara Unduli would be non-existent, and the Clone Wars could have been won by the Separatists at the Battle of Geonosis; not to mention the prime architect on the Death Star was a Mirialan.
Each one of these races contributes to the development of one's character's background, and seeing as everything is story-driven, I think that counts for something. Each one has the same basic body shape because 98% of species in Star Wars have the same body shape; why did humans evolve the way we did? Because our morphology has proven to work, so why couldn't it work in 98% of everywhere else? Next time you rant about something, you can be self-righteous, but make sure you aren't in supreme ignorance at the same time.
