mBTC could potentially be helpful in promoting broader user engagement due to the current lack of understanding by the general public that bitcoin can be bought and owned in fractions. More bitcoin owners hips will likely result more transactions, more liquidity and thus better price stability. I see some merits in it.
I don't understand why this argument is so prevalent. So long as people can't use credit cards or paypal to buy bitcoins, the biggest barrier to a small buyer is the necessity of using a wire transfer or linking their bank account to some exchange. With the media portraying bitcoin as drug money, is anyone really going to want to associate their bank account with some sketchy exchange? Bitcoin appeals to fiscal conservatives, and it follows that fiscal conservatives would be generally conservative.
http://www.psychologytoday.com/blog/the-human-beast/201104/conservatives-big-fear-brain-study-findsBitcoins sketchiness is the biggest deterrent to small investors.