Similar like to much abstraction is considered harmful for code readability, same thing apply to too much simplification (because you basically add layer on top layer and you introduce complexity).
Session facade is useful in situations where it encapsulate the complexities between the client and the server interactions. It manages business objects and provides uniform service access layer to clients. It basically represent centralized peace that minimize method calls over network, exposes uniform interface and managing security and transactions in one place.
