Origin or not, the usage is completely different. Tyrannosaurus is a word that has been around and used in fantasy for probably as long as fantasy has existed as a genre. Or at least pretty closely. Necromancy and Thaumaturgy have been part of the genre and the game for decades.
Technobabble words like Psychometabolism have no such history to stand on in the genre.
The roots of words like "psychometabolism" probably predate the existence of fantasy as a distinct genre- if you go back to the roots of genre fiction- pulp, horror, fantasy & sci-fi- you'll find that the genres used terminology pretty interchangeably.
My personal stance on the oddness of the names in the Psionic system is this- as has been stated before, the roots for things like "Psychometabolism" date back to ancient Greece. They may have even been actual words...but used in a different way.
For instance- the concept of the mind controlling the body goes back a loooooong way. A "psychometabolic" condition could have been used in much the same way as "psychosomatic" is today...the person is affecting his body via his mind- for good or ill, consciously or unconsciously.
Others that meld ancient languages with modern concepts are still problematic- like, say "biofeedback"- but beyond the name is still a concept that would have been recognized by an ancient "Natural Scientist" (a term going back thousands of years, BTW)- toughening up one's body for combat by mental concentration.
The solution? Call "Biofeedback" a "Ki Trance" or "Body of the Dragon" or some such.