A milliBTC is going to become a common unit, since it is going to be more or less scaled to similar amounts of USD or EUR. If you want to want to use a word for a milliBTC that does not have a current definition, more power to you.
Yes, I want to call what we now call A) 1 satoshi or B) 100 satoshis a BITCOIN and what we now call a 'Bitcoin' should be called a "full _____ of Bitcoins". We could even call it a "Full
bar of bitcoins".
That makes as much sense as saying "kilometer" is too unwieldy of a term in describing terrestrial distances, therefore we should start calling kilometers "meters".
Small b bitcoin describes the protocol and a word attached to the value, big B Bitcoin will be a rare unit of measurement, such as the volume of trading at Bitstamp today was 16,000 Bitcoins, or that the Winklevoss Twins collectively own over 40,000 Bitcoins. Regular people will spend 150 mBTC paying a monthly cell phone bill, or buy a new laptop for 1500 mBTC.