While my experience with K'hara has been mostly negative in my opinion, I can name several occasions where interaction with them did consist of more than just red-is-dead'ing. Telepathic tomfoolery, "forced" visions, attempts at what I can only assume was supposed to be indoctrination. That sorta stuff. Admittedly, it's rather rare and most of my encounters have just been PvP-focused.
As for Nomads regularly adding to the RP environment, look no further than the Nomad Vagrants. They are explicitly, canonically not PvP-bots. While the quality of their RP varies, it is generally quite pleasant (especially since they forego that god awful Nomspeak) and rarely ends up in violence unless non-Vagrant players want it to.
Edit: I have to admit, however, that I agree that Nomads should never have become available to players, though for more reasons than /1 /2 bad.