Leatherhead
Possibly a Idiot.
Their extra class and subclass abilities can be weaker.
There is no way that kind of design angle works in the modern day.
If you make them noticeably weaker than traditional classes then the psionic fans will riot, and any potential new fans will be spurned for yet another edition, an edition that is shaping up to be the longest one yet.
If you don't make them noticeably weaker then they will be shunned because they are broken, again. Regulated to the pile of bad ideas that nobody learned any lessons from.
And either way it isn't going to get up to that magic 70% approval rating because it lass mass appeal.
It's just a non-starter. Psions are just going to have to use concentration, a focus, and have some kind of display when manifesting their powers. Sure, it might not be a chicken dance with bat guano being flung across the room, but it will have to be blatantly obvious and able to be shut down with mundane means in some other fashion.