#5 seems like the deal breaker to me for a lot of use cases. The average user is not nearly savvy enough to be trusted to secure their private keys. I can't count how many of my non-tech friends have been locked out of their email accounts or fallen prey to some kind of password fishing attack. With centralized solutions they still have a reasonable chance of getting their account or data back. With a blockchain they are screwed. For most consumers this will be more than enough to scare them off.