From: Tom Lane
It's probably mostly historical accident :-(. There have been
suggestions
before to convert more system catalog columns to regfoo types, but
there's
serious stumbling blocks in the way:
Thank you so much for concise detailed explanation of the history and
current situation. I understood that it would do more harm than good
to change existing plain oid columns to reg* types for various
clients, and it wouldn't very beneficial but also not so harmful to
make new catalogs/columns reg* types.
Regards
MauMau