The only thing that needs to be made perhaps more "average user" friendly is the way bitcoins is stored and spend.
Which is probably solved by using a site instead of a wallet on their PCs. After all, storing in the cloud makes much more sense for average users.
The mining aspect will allways be for a select few, we do however need a huge influx of users who intend to make bitcoins their primary currency(lets hope) oneday to pay for products(online at first) and not specificly to play the market(mining,mtgox etc) and profiting from bitcoins.
Yes, mining is specifically off-limits to new users. They shouldn't even be thinking about it. There's a good reason why it was removed from the original client

And indeed, why would they have to understand how the currency works under the hood? Rarely anyone understands how it works with money printing/federal banks in their own country.