But the number was low and new names could be easily added.

Agreed. Adding new ops is not a problem. Alphabetizing the oplist and renumbering the ops was unnecessary.

There was never a public discussion about this policy change.

I remember several public discussions, at least in multiple #ps meetings.

If PBC now is not sufficient after the third rewrite what is still missing?

The last time I looked at PBC, it was still too tightly coupled to the internal layouts of various PMCs, especially the Sub PMC.