I think it should be a feature:
rpm -e <pkg> doesn't remove compressed manpages. man can
handle compressed manpages, so the better way is:
a) setup compressed manpages in packages or
b) add flag to rpm to remove compressed manpages.
Rpm removes *only* files that are in a package's file list. If you
want generated man pages to go away, set up a daily cron job that
automagically removes files older then N days.