the rest of the world is, why cant we?
imperial has caused some complications in the past, including the loss of millions of dollars because of space mission failures due to miscomunication of the units in which the thrust/fuel load/weightload etc was measured in.
metric is also easier to deal with, because it is in units of ten, which is by far like the most wholesome number in terms of division and multiplication.
as well as that, it was also put into use as a way of confusing our enemies and separating ourselfs from other countries. we dont need to do that anymore, so why keep it?
all this being said i think we should switch. but that would also cause some complications:
-we would have to recode everything in the US that uses imperial
-we would have to repaint ever mph sign in the country
-we would have to redesign our cars
-we would have to relearn an entire new way of measuring things, which will be hard considering the imperial system has been engraved in our brains for so long
just some things to think about :)