Mecheon
Sacabambaspis
Pretty much agreeing with this. Psionics is its whole field and, well, other classes can semi-get itThere are tropes that make D&D what it is, and a psion/psionicist class is one of them. Not as crucial as fighters, rogues, clerics, and wizards . . . but still important to many long time fans.
Mind I'm happy with third party offerings at present so I haven't been too fussed but, there is still a gap for a psionic class to fill