I don't think "unlimited" plans ever made much sense because some people will abuse it.
If something is advertised as unlimited how can you abuse it? You are placing the blame on the wrong side of the equation. Lets look at it this way... An air carrier over books a plane, and all passengers show up for said flight. By your logic it is the passengers fault that someone will have to be put on another plane. If the network can't handle unlimited use then don't advertise one. Or you may just over book the network and some passengers/packets will have to wait for another flight/pipe.
There are never any bugs you haven't found yet.