How many times have you loaded the barracks up with one type of military unit, only to find you need a small quantity of a different type?
The pain of clearing one lot at a time is frustrating, to say the least. Years ago, you could at least clear 3 lots at a time, but BB took that away and made it one click every 4 seconds to clear each lot.
How hard could it be to have a "Clear Queue" button in the barracks?