So what does a world look like that includes both Magic and Psionics. And no Dark Sun -- making magic The Bad is cheating. I mean your typical D&D world that happens to also include psions alongside wizards, clerics and druids. How is that distinct? How does it MATTER?
Well, since you asked. (I typed this up in another post a while ago, but i cant find it, so I shall attempt to repeat here)
My world has had psi and magic since 1986. And to be honest, perhaps in your view I cheated, cause I made psionics The Bad.
Basically established two standards for psionics in the world.
a. psionics is evil (its not). But people treat it as such cause they are familiar with spellcasters (to an extent) but being charmed by mental power without sight or sound means the villain could be anyone. Giving, among the basic populace of the world, psionics the "evil, witch, burn it vibe." Example of psionic creatures such as Mind flayers, aboleths, and githyanki didn't help.
b. psionics is enlightenment, the power of the mind and the path to the power of the gods. People believe/worship gods. Sounds like a mental flow of energy to me. And as reality altering beings of power, gods might not encourage mortals learning, or manifesting psionics.
There are places that know better (psionics is neutral like everything else) and a few temples that don't mind.
a.2 wizards don't trust it either. Seems suss to them.