The default value for MaxExpansionDepth in Web API is set to 1. Although this works on most of the cases, having a default expansion value of two is much more reasonable, as it can cover scenarios like a client querying for a Customer, it's related Orders and the Details for those orders.
In the Web API preview, there wasn't support for nested server pagination of a IQueryable, so this limit had to be very conservative as it could cause a serious performance penalty on the service As nested pagination has been implemented for RTM, it makes sense to be more permissive with this limit, as for example, if we stablish a page size of 10, and an expansion depth of 2, the maximum number of objects that a client could retrieve in one request would be 1110 considering he sends a query like query?$expand=Orders/Details
In the Web API preview, there wasn't support for nested server pagination of a IQueryable, so this limit had to be very conservative as it could cause a serious performance penalty on the service As nested pagination has been implemented for RTM, it makes sense to be more permissive with this limit, as for example, if we stablish a page size of 10, and an expansion depth of 2, the maximum number of objects that a client could retrieve in one request would be 1110 considering he sends a query like query?$expand=Orders/Details