Those of us who have more experience with OpenWrt know that it is a bad idea to use opkg upgrade (unless there is a very specific reason) as things can break. But many other users do not know -- they assume that it is just like any other linux installation and that the upgrades should work most of the time.
With that said, is there a way to safeguard opkg upgrade on OpenWrt. I'm thinking of something like the Voltaire/Spiderman warning that comes up the first time a user types sudo in many linux distros. ("Are you sure you want to run opkg upgrade? This may break your OpenWrt installation.") Or possibly require some additional argument (maybe '-force') before it will do anything. The idea is to warn the user or to make it necessary for a novice to look up (on the OpenWrt wiki/documentation/forums) why it isn't performing the upgrade (at that point, they are informed of the risks, but the tool still works).
It probably would be bad to to totally cripple or remove the functionality because there are legitimate times that this could be useful, but it seems to cause many users serious headaches.
FWIW, I am not a developer, just an enthusiastic user and contributor on the forums... so I wouldn't be the one to implement such a change. Beyond that, there may be good reasons to not mess with it -- things I wouldn't know as a non-dev type.