Issue: Why should not there be a relationship among ports in a Service?

Section 2.7 Services states:

"Ports within a service have the following relationship:

   *   None of the ports communicate with each other (e.g. the output of
     one port is not the input of another)."

This seems to be an unnecessary restriction. What is the justification
for it. Some of the specs that are built on WSDL seem to already violate
this rule. Example excerpt from the XLANG specification:

<service name="StockQuoteProviderService">
                      <port name="pGetRequest"
binding="tns:RequestReceivePortBinding">
                        <soap:address
location="mailto:quote@example1.com"/>
                      </port>

                      <port name="pSendResponse"
binding="tns:ResponseSendPortBinding">
                        <soap:address
location="mailto:response@example2.com"/>
                      </port>

                      <xlang:behavior>
                        <xlang:body>
                          <xlang:sequence>
                            <xlang:action operation="AskLastTradePrice"
                              port="pGetRequest" activation="true"/>
                              <xlang:action
operation="SendLastTradePrice"
                                port="pSendResponse"/>
                              </xlang:sequence>
                            </xlang:body>
                          </xlang:behavior>
</service>

I would like to suggest that this restriction is removed..

Thanks, Prasad