Add-on software; not stuff that comes from the OS repositories. Which is why on a conventional Debian/Fedora/etc. system with all the software coming from OS debs/RPMs you'll find a completely empty /opt. That's also rather built into the assumptions that maemo-optify makes, since it will refuse to modify any package that's already using /opt for anything, so as designed it will only function on debs that don't use /opt directly.