It's not odd if you consider that a lot of electric drills from that period - maybe the majority - were used in commercial/industrial settings. 220 volt power allows for lighter gauge wire for a given net output, not an insignificant issue if you're wiring an entire factory.
Of course, electric drills from that period often lacked equipment grounds, using the mechanic holding them as the equipment ground if a fault occurred, and the mechanic lights up more dramatically; so there are arguments for 110 volt power, too.