Well, that kinda depends on how you see the classes. Like do the people in the setting really see psionic sorcerer and dragonic sorcerer to be same type of thing any more than they see a druid and bard to be the same. Now I fully get the sentiment of wanting the classes to be actual, coherent classifications that have some meaning in the setting too. I really want that, but that's not the only way to look at things. But yah, if we think that psionics is at least as different from arcane than arcane is from divine, then it is indeed a bit weird to have the psionics to be just tacked on as subclasses to arcane classes. Like there isn't some cleric subclass that suddenly becomes arcane caster. Then again, there is already the divine soul sorcerer...