Sorcerers are more popular than Wizards, but I've had both in campaigns with psionics (both regular psions and wilders). I've allowed psionics since the books came out. Usually I don't get both psionicist and arcanist in the same party, because they all fill the "spellcaster" niche, but the PC's freely switch between and the enemies run the gamut as well.
I've never disallowed psionics, and I've never had a problem with people still playing the other spellcasters. But since they don't HAVE to, they only play it if the concept fits.