Web servers are different from game servers. You need a lot of performance and fast low latency servers to keep up with realtime game play. Webservers however dont need that and can benefit of load balancing accross multiple servers. Scale of economy helps a lot, but with game servers the cost doesnt change much because a session has to be on a single machine.

As for distribution costs, most of the cost is manufacturing and physical distribution of discs. So yeah, they are making a killing by continuing to take a a huge cut from game sales when most of their distribution is online.