D&D 5th Editon Discussion: 6th thread and counting

[PairO'Dice Lost]

Psionics have never been considered an integral part of any edition.

I'd disagree there, to some extent, since psionics had enough of a presence in 1e to make it into the PHB as an appendix (with every PC theoretically being able to gain psionics), into the DMG in the form of psionic combat tables and different timescales, and into the MM with many monsters having innate psionics including many iconic D&D-original monsters. Very integral? Not necessarily. Iconic, and extricated from the core rules only with some difficulty? Certainly.

But your larger point about psionics and other subsystems likely being splatbooks at best in 5e is granted.