Using 'milli' and 'micro' for money is unfamiliar and confusing to ordinary people. especially micro with the added μ u confusion.
What's the problem with this approach?
Honestly? I suspect it's bikeshedding: http://en.wikipedia.org/wiki/Parkinson%27s_law_of_triviality. We want Bitcoin to succeed, we want to help it succeed, and we instinctively feel that the way we can make that happen is by "making it easier for other people". Tinkering with convention seems much easier than starting a BTC business, building an innovative platform on top of Bitcoin, etc. If I wanted to start a BTC business I'd have to come up with a business plan, find investors, purchase equipment etc. But this - all I need to do is have an opinion. I don't even need to research the demographic I believe I'm "helping".
This is my concern with this issue. I have no idea what works for anyone but me. None of us do (well, obviously some of us have some - limited - idea about our customers. But hopefully you get my point). Our preferences, or what we think others might prefer, won't work for many people - perhaps not even the people we think we're helping. My solution is to leave people alone, and give them the freedom to adopt whatever system works for them - Satoshis, kiloBTC, whatever.