I can only expand on what John has already offered. If the service delivery of an organization is hardware to the user desktop or customer then THAT should be the focus. My guess however is that the users are interested in the applications and the data that feeds in and out of those applications. In most cases, and hold on techies, the customer really doesn't care about the hardware, only the tools they need to perform their jobs.
Now, techies rejoice, because there is no way you can create an application focus without consideration for the hardware. The reverse is not always true. A hardware-centric strategy could overlook critical components of an application or data stream.
Another critical consideration is the customer link. Hardware support teams don't generally have a line of communication with the end users. This communication channel is the life blood of application support. The App Team translates business requirements into support solutions so why wouldn't you want to tap that precious resource?
I've worked in both environments and, without a doubt, I saw the most success working in an application driven environment. In fact, the application custodian would be assigned responsibility as the recovery team leader. No one other than the customer knows the desired end result better than they do.