I would give a few reasons. Immature front ends, most people can't be trusted to handle their own email password let along a wallet private key that has their live savings in it. We need a better way. Speaking of security, too many people can't be trusted with their own keys on their own digital systems. People lose their passwords and get hacked all the time, imagine if that also meant financial disaster. Like it or not, at the moment, people like the 3rd party middleman to come in and fix things up when they get screwed up!
Volatility, it is just too uncertain (from a 1st world perspective) to know what the value of your crypto is going to be tomorrow or the next month or the next year. Until there is a bit more stability in the system (not just price, but the culling of all the crypto to the ones that are actually survivors), I don't see a mass adoption.
Agreed that crypto gives us freedom... but most people don't want to have the freedom if it means being responsible for everything!