Description of problem: People who are using rpm -i/-U/-F instead of yum are now not getting any data into the yumdb, so it seems like a good idea to issue a warning (if stderr is a tty) if someone uses those options. I assume this would be Fedora specific, or maybe a compile optional. We don't need to go overboard, just something like "Unless you know what you are doing, you probably want to use `yum install blah' instead".
Sorry but no, rpm is not going to illegitimize or deprecate itself installing and removing packages. If you want to have such warnings, put them into yum itself: a warning in rpm wouldn't prevent the install/erase, so yum would complain anyway on next operation. So you have the same chance at educating the average Fedora users to prefer yum over rpm as rpm would have, without polluting rpm default output with messages that dont belong there. In other words, just make the warning discussed in bug 530781 more to the point.