I was a little bit shocked to learn that many (if not all) hosted e-Wallet providers combine their customers money in the hosts account, instead of just providing a service for easy access and storing of the users wallet data. This carries over many of the well known and less well known problems with the traditional banking structures onto bitcoins, and defies the aim to avoid central services. So, what are the actual advantages of this, for both the user and the e-Wallet service?
For the e-Wallet it would allow fractional reserve banking in order to charge interest for loans. That makes the system susceptible to crashes like we are experiencing outside and supports an interest based economy, which has its own troubles. (See also this question.) And it makes it easier for the bank to run away with the users money, since the users give the actual ownership of their money away. Are there other points? What is the advantage for the users?