In either case, it's out of place.
If psionics is magic, it's redundant to magic.
If psionics isn't magic, it's game breaking, and adds an unnecessary complex system.
Whether it's game breaking is up for debate. And it doesn't have to be unnecessarily complex.
If it is magic, it might be redundant, but then so would overlapping mage and cleric spells.
The problem I see is that over time D&D has supported both versions. Some of us like the not-magic version and some of us don't. Most of the discussion has been trying to force one position on the other, but in it's broadest sense it's just arguing fluff. It just so happens that the fluff happens to have very broad mechanical implications if we choose one side or the other.
If you want to argue sorcerers and psions are basically the same, as has been going on in other threads, I'll disagree with you. But, if you say in your game psionic power and sorcery are indistinguishable, fine. I'm ok with that unless you try to force your game ideas on me.
Can both positions be mechanically viable in a single edition, or is there a line in the sand that needs to be drawn?