The Raiders were never anything more than generic bad guys to knock down when they didn't have anything bigger to aim at, anyway.
JMS's DVD commentary for "Signs and Portents" includes some hilarious lines about how the Raiders are just generic bad guys. There was a line along the lines of "The Raiders are just sitting around, having a beer, until I call them to serve as stock bad guys."
Also, on the psychic/telepath question....."psychic" has a pretty distinctive definition, separate from "telepath". The Psi Corps is made up of telepaths, not psychics.