The most amusing thing to me about D&D psionics is that it was created specifically to address the two major perceived failings of D&D itself after it’s first year: at first a lot of people hated the class system, saying that the three classes (fighting men, magic-users, and clerics) were completely unrealistic (despite the options for races - even Gygax said in the very first book that people could start playing as a dragon, so long as they started weak, and later classes swiftly added on in various sources)…
…and that Vancian style spell-casting (memorize and forget after casting) was unpopular, and they wanted a point system instead.
Thus psionics was specifically crafted to address exactly those two points - it provided something not tied to any class in exchange for certain class features, and it ran off a point system. It was also extensively playtested before being released. Sadly, it introduced a few new problems as well. It didn’t match the look’n’feel of the rest of the game, and a lot of people were apparently bothered by the 60-70s parapsychic terminology being used despite the fact that there were a number of spells which did the exact same thing.
Which is a shame as the 0e psionics system was surprisingly streamlined and easy to use with simple combat rules, lightning fast resolutions, and realistic limitations on actions taken and affecting non-psionic targets. Too bad those rules were presented as “additions” to the previously existing rules by section, and as such were scattered into those various sections making referencing it a pain. It was by far easier to use than the spell casting system.
1e psionics tried to fix the new problems, providing more details and clarifying text, as well as addressing the complaint that ‘psionics should happen at the speed of thought’ feedback from customers.
2e saw the temporary removal of psionics, until it was brought back, and I quote, “by popular demand” in The Complete Psionic Handbook. It became a skill based system, and the combat modes became powers. Now people were complaining about it the fact that almost anyone could potentially get psionics, so it was tied to a class and it got rid of the ‘acting at the speed of thought’ concept when that proved to be wildly unpopular in the end.
When the skill-based system was complained about, it was converted to a combat system with the introduction of MTHAC0 later on in 2e in the newer Dark Sun updates to psionics, and the skill aspect was removed.
People still complained about it being a totally separate system from the core concepts of the game, so in 3e it was tweaked to use the same ruleset as magic. The combat modes were reintroduced.
3.5 psionics also incorporated the feedback from 3.0, Combat modes was removed again. Now people complained about it using the same ruleset (it’s an alternate spell system) even though that was what they had been asking for (in aggregate).
4e saw psionics converted back to a power based system.
They beta tested a bit in 5e, but never settled on anything.
6e/next/beyond/whatever is apparently still playing with the concept.
Unlike much of TSR/WotC, the psionics system was one area where listening to fans actually happened - as Gygax disliked the idea of psionics in his medieval fantasy, he assigned it to others to continue to develop. Sadly, psionics as a system gained a poor reputation that was cemented in the collective gaming consciousness and it never really escaped that shadow.
Ironically, they probably should have simply decided what psionics should be to D&D, and then stuck with those concepts and honed them. Obviously, listening to the customers in every little thing pleased no one in the end.