I want M4-78. It's the droid planet that was supposed to be in KOTOR II, but they cut it out. That's right, they cut out the whole planet!
The least they can do is put it in next game in series.
As for Korriban, you were supposed to meet one of your party members there. He was intended to be a Devanorian Jedi that came to Korriban to hunt Sith, but he found the empty academy, and moreover, he was tempted to Dark Side by the Valey of the Dark Lords. You would bring him back to light and he would join you. They cut that out and put the Disciple in his place.
