In many areas they would probably violate local building codes that require the use of a standard socket.

For wide acceptance they would have to overcome that, and get hotels to replace every socket (or it looks like they are big enough that one of them replaces two regular sockets here in the US), which I just don't see current buildings doing. Maybe new construction where you have to put in every socket anyways, but it just won't be worth the expense for them to do it.