Yeah, the issue is that the people who make the most noise about psionics 1) don't want it to be just spell magic and 2) want it to be as powerful and flexible as spell magic.
I mean, sure, a psionics system fully equivalent to the 3.5 XPH is easy. You rename the 5e sorcerer class "psion", use the DMG spell point option, create new subclasses for different flavors of psion, modify the spell list a bit, and replace the spells' verbal components with audio manifestations and somatic components with visual manifestations.
But anyone who would be satisfied with that mostly doesn't spend a lot of time talking about psionics on message boards.
Similarly, except for psionic combat (which was always a broken pile of brokenness), a system basically equivalent to OD&D or AD&D 1st edition psionic powers is pretty easy . . . because the obvious 5e mapping is single-power feats, maybe some psionic subclasses. But that sort of psionics is too restricted and weak to support a psion class (note neither OD&D or AD&D 1st edition had one), and well, as of Tasha's, we already have it anyway.
Rather, what the loudest psionics fans want is a whole alternate power system as powerful and flexible as spells but mechanically distinct, like the AD&D 2nd edition psionicist. Which means, in the practical realm of actual game design, something that will be too complicated and too unbalanced to be allowed at the vast majority of D&D tables, like AD&D 2nd edition psionics. And thus something with an inherently limited sales potential, and thus vanishing small likelihood of WotC ever publishing.
(Anything new, but merely just as complicated and just as unbalanced as the existing spell system, is too complicated and too unbalanced to gain wide acceptance. A new system inherently doesn't have the spell system's advantages of already being known and having been designed around. As a result, it would have to be simpler and more balanced to get wide acceptance, criteria that are in tension with each other and with the system being simultaneously as powerful and flexible as spell magic.)