SOA/ESA strategy: which benefits inside company

Which benefits bring SOA for company?

If I want to expose some logic (HR module, Finance) I could get all I need (loose coupling, abstraction, transformation, routing, business process automation, long running process) with ESB facility of SAP XI and Adapter Engine or RFC,IDOC and so on.

Why we do need SOA?

I can find only one benefit - in case I want to give an access for business partners, vendors, customers and so on...

What do you think Do we need SOA inside company?