It's the only way I was ever able to explain my father's love for blood sausages and Brussels sprouts.
Me, I'd be happy with a psion as a distinct class or with psionic elements of a lesser kind salted throughout the extant classes: the thing I don't want to see is the psionic abilities becoming so OP they overshadow the rest of the game: this was the exact problem friends and I encountered in 1e. So long as it's reasonably balanced, I'd enjoy a distinct psion class. Lots of complexity probably wouldn't bother me, either, but I do think it'd be a bad idea insofar as WotC wants to extend the game's reach as far and wide as possible, and needlessly baroque rules systems undermine that.