I'm not sure that changing everything to a mBTC standard would help anyone who doesn't know much about BTC. However, I can see where adding the option to buy in units of mBTC may have the effect you're looking for.

Something like this:

Buy 1 BTC = $1,000
Buy 1 mBTC = $1

or even buy 100 mBTC = $100

I believe the "100 mBTC" vs "0.1 BTC" may have a more positive effect on someone unsure of getting started.

Though, this all begs the question, does BTC need new support by people just flat out buying into the market?