I am in fact not just jedi, I am with the Sith. I do have jedi powers (such as force choke), and I also carry 2 lightsabers and a dualsaber for backup. And I love the wonders of Korriban, you really should visit it once. Go to the Valley of the Dark Lords and enter the temples. Maybe you even have a nice chat with Ajunta Pall. Just like me.There is also much to study there, artifacts to be found. With the republic the jedi council would never have allowed us to visit the planet and they would have let the ancient knowledge to be forgotten. And they even tried to destroy the StarForge. Fortunatly, I kille my former apprentice (after he betrayed me and took the SF) and defeated the jedi fleet, thus saving the SF.
And why should non-humans join the rebels. The Empire tries to improve life for all species. Haven't you noticed the wookiee-shave-program? Or what about Thrawn, he's not human. Do you want to tell him that he shouldn't have joined the Empire, that he shouldn't have been a Grand-Admiral?
And yes, idealism is a much better reason to join the Empire than being one of our heroic stormtroopers or TIE pilots. And really every single idealist should join the Empire.