To me that's an argument for making it an addon to existing classes (either as subclass, or Feats). If you add psionics to fighter, for example, then if one fighter takes telekinetics, and the other fighter takes mind-reading, and one of those two is "better" than the other, that's ok, because hitting things with swords is their main function, and the psionics are just frosting.
Overall I like the idea that those with psionics are really good at one subset of psionics, and maybe sorta good at one or two other things.
(Note: yes, I recognize that the above model does is not what the current UA does.)