Why are default encoding conversions namespace-specific?

See $SUBJECT. It seems to me this is a bad idea for much the same
reasons that we recently decided default index operator classes should
not be namespace-specific:
http://archives.postgresql.org/pgsql-hackers/2006-02/msg00284.php

I don't mind having encoding conversions be named within schemas,
but I propose that any given encoding pair be allowed to have only
one default conversion, period, and that when we are looking for
a default conversion we find it by a non-namespace-aware search.

With the existing definition, any change in search_path could
theoretically cause a change in client-to-server encoding conversion
behavior, and this just seems like a really bad idea. (It's only
theoretical because we don't actually redo the conversion function
search on a search_path change ... but if you think the existing
definition is good then that's a bug.)

Comments?

regards, tom lane