Retrieve related entity records along wih the Primary entity using Retrieve Method

We have always known the Retrieve request to be able to retrieve the data of the requested entity based on the id provided. However in CRM 2011, the Retrieve request can read not only the properties of the primary entity but also the referenced entity like in a 1-N or N-N or N-1 relationship. Given that it supports all the three types of relationships it could be an advantage over the LinkEntity feature.For example, if we want to retrieve the active contacts related to an account then, we can design the query as shown in the below code,

using (OrganizationServiceProxy _orgserviceproxy = new OrganizationServiceProxy(new Uri(OrganizationUri), null, Credentials, null))

                {

                    //create the query expression object

                    QueryExpression query = new QueryExpression();

                    //Query on reated entity records

                    query.EntityName = "contact";

                    //Retrieve the all attributes of the related record

                    query.ColumnSet = new ColumnSet(true);

                    //create the relationship object

                    Relationship relationship = new Relationship();

                    //add the condition where you can retrieve only the account related active contacts

                    query.Criteria = new FilterExpression();

                    query.Criteria.AddCondition(new ConditionExpression("statecode", ConditionOperator.Equal,"Active"));

                    // name of relationship between account & contact

                    relationship.SchemaName = "contact_customer_accounts";

                    //create relationshipQueryCollection Object

                    RelationshipQueryCollection relatedEntity = new RelationshipQueryCollection();

                    //Add the your relation and query to the RelationshipQueryCollection

                    relatedEntity.Add(relationship, query);

                    //create the retrieve request object

                    RetrieveRequest request = new RetrieveRequest();

                    //add the relatedentities query

                    request.RelatedEntitiesQuery = relatedEntity;

                    //set column to  and the condition for the account

                    request.ColumnSet = new ColumnSet("accountid");

                    request.Target = new EntityReference { Id = accountID, LogicalName = "account" };

                    //execute the request

                    RetrieveResponse response = (RetrieveResponse)_orgserviceproxy.Execute(request);

                    // here you can check collection count

if (((DataCollection<Relationship, EntityCollection>)(((RelatedEntityCollection)(response.Entity.RelatedEntities)))).Contains(new Relationship("contact_customer_accounts")) &&((DataCollection<Relationship, EntityCollection>)(((RelatedEntityCollection)(response.Entity.RelatedEntities))))[new Relationship("contact_customer_accounts")].Entities.Count > 0)

return true;

else

 return false;

 }

One limitation though, is that it is only available with the Retrieve Request and not the Retrieve Multiple request. Wonder why this has not be added for Retrieve Multiple request as this can be of great help to return all the data required in one request.