PMs != the general forum. Yes, Mystic and anyone with database access can read your PMs, but in general, PMing keeps things private, as in Private Messaging. As you aren't crowding up the forum, if you and a friend want to set up a netgame through PM, it should be fine. Obviously, this isn't a license to spam every member with "netgame plz", but oh well.
Besides, we barely have enough admins to cover our public posts-I doubt any of them will take the time to read PMs uinless necessary (or addressed to them :p).