Just another salvo in the Microsoft vs. OEM battle that's shaping up.
These deals exist so that large companies can buy something like the Surface Pro and have it supported in a similar fashion that their business desktops, laptops and servers are. Call and file a ticket with a single vendor, and the hardware magically gets replaced. Since there's practically nothing to repair on a Surface Pro, that just means HP and Dell do the sparing needed to get machines to customers fast.
I guess that for a global company that has to service these everywhere, it's not an option to just go down to the Microsoft store and make an appointment...