But how does this help the 4 billion people currently without addresses? Do you think there are rich geographical datasets in places without addresses?
Even in places like the US where you do have rich datasets, it is still enormously inconvenient to not be able to do anything without them. The advantage of 911 & USPS street addresses isn't that they're easy to remember, it's that they encode a lot of useful information into them. (And even then, they don't include all useful information -- you typically need to know some ill-defined political or social boundaries, like the name of a neighborhood, to find out if someone delivers to your area or what the rate is for a taxi.)