IDK about the witch, but I was thinking about what characters with psionic classes USED to be capable of and decided to dig out the last psionic character i ran in, which was a battlemind in 4e. For the sake of comparison, I'm looking at what she could do at level 12, which would be the equivalent of a level 8 character in 5e.
The psychic warrior in 5e is a fighter and consists mostly of fighter features, with a little bit of damage or defense at level 3 in the form of psychic armament along with mage hand, and strength of mind, which gives a ranged force attack with CC that you can use a few times a day.
My 4e psionic warrior at a similar point in character progress has around 17 powers just from class or paragon path. She can invade an enemy's mind, penalizing them for attacking allies with battlemind's demand, at-will. If they attack an ally, she can damage them mentally with mindspike or shadow their movement with blurred step. Concussive spike, lodestone lure, and psionic speed are all at-will attacks (cantrips in 5e) that can push groups of enemies 20 ft (!), pull an enemy 10 away closer with a hit, or lash out with a flurry. She can create a nightmare zone that essentially generates a telekinetic whirlpool around her, split time to move an attack enemies on their turn, and break time with an accelerating strike as she moves through enemies. She's got a short rest teleport that surprise a target, plus there's a little bit of flight and psychometabolic defense in there too.
I don't expect a 5e psionic class or subclass to have 17 features at level 8, and I'm not really looking to go back to that level of complexity. But, I really really would like to capture some of that flavor and a fighter subclass just doesn't have close to enough room to fit super powers in there.