...as much as the intelligentsia want to whine about it, the bulk of the US uses imperial systems in their daily lives.
There is NO compelling need to mandate a switch. None. The bulk of the people in the US who need metric, or need to convert units, or deal with the rest of the world can use either one without an issue (and already do).
For you true utilitarians out there, then, who firmly believe that we should switch to metric because it would simplify massive world systems immeasurably if everyone was simply on the same standard...I'll switch to officially metric the moment you all switch officially to English. Because the benefits of monolingualism are PRECISELY the same (or greater) as the stridently-cried reasons for Metrification.