Why don't we allow DNS names in pg_hba.conf?

I was reminded of $subject by
http://archives.postgresql.org/pgsql-admin/2006-01/msg00002.php

While I haven't tried it, I suspect that allowing a DNS host name
would take little work (basically removing the AI_NUMERICHOST flag
passed to getaddrinfo in hba.c).  There was once a good reason not
to allow it: slow DNS lookups would lock up the postmaster.  But
now that we do this work in an already-forked backend, with an overall
timeout that would catch any indefinite blockage, I don't see a good
reason why we shouldn't let people use DNS names.

Thoughts?
        regards, tom lane