Psionics have a biological psuedo-science explanation for why they work at their root. They're science fiction, regardless of the type of fantasy they show up in.
That strikes me as an arbitrary and unclear and undiscernable distinction. Is animal husbandry, then, a science fiction field rather than a fantasy one? If I breed griffins in my fantasy setting to be larger and faster fliers, am I not using principles of biological pseudo-science?
But if we're going to drag up and debate every thematically dubious name in D&D, we'll still be arguing here when 5E is released.
That statement doesn't mean what you think it means.
Thematically dubious? How about thematically definitive? I came to D&D after reading stuff like Tolkien, Lloyd Alexander, and stuff like that, so I initially wanted a very "pure fantasy" take on the game. The fact of the matter is, D&D is a poor choice for that, because it was never a design goal of D&D to emulate that kind of setting, and it doesn't really do it well. You either wrestle constantly with the square peg and round hole nature of your situation, or you pick a different game other than D&D, or you embrace the inherent thematic diversity that ranges from fantasy to science fiction, to horror, to weird tale, to mythology, to sword & planet, to Arthurian romance, to Tarzan to... well, all the crap that's in D&D and always has been.
I think you're wanting D&D to be something that it's not really and never has been. I'm with you; I've certainly been there, and after coming around the bend and approaching it from a different angle, I'm there again for completely different reasons... but at some point, you call a spade a spade.