people arnt really used to talking about milli/micro/nano, especially when dealing with money..
Everyone (except possibly some people in Liberia and the USA) knows the difference between a meter and a millimeter or a liter and a milliliter. Understanding bitcoins and millibitcoins will be just the same and going from there to microbitcoins is pretty straightforward.
But there's still a fairly big issue with 0.xxxx values. They are very difficult to read because unlike large numbers we do not split them up using commas.
For example 1,000,000 is fairly easy to read as being 1 million. Whilst 0.0000001 isn't easily recognisable and I doubt most people would know the SI unit... :/