Because there are no sci fi racial tropes, that aren't under copyright.
I wouldn't say that. Most of the copyrighted races can be boiled down to their basics without running afoul of copyright law.
You can have mindless hive-based aliens who just want to eat your flesh.
The standard proud warrior race, mired in ancient tradition.
The highly advanced, peaceful, meditative race who view us as children (bonus points if they have a deadly and violent nature which they suppress).
Some kind of AI or Robot race.
Parasites that take control of their host.
Theres probably more (hunter aliens, the standard anthropomorphic animals etc) but I can't think of them off the top of my head.
But that aside, I don't mind the fantasy races transplanted into space. It's interesting enough (plus space dwarfs are totally rad).