Why does the SP2 installation require SP1 be installed first?
There are a number of reasons for this, the primary one being the overall size of the standalone package for SP1. Having a cumulative SP2 that includes the updates from SP1 would have made the size too large. Furthermore, because SP2 is a single-servicing model, and since Windows Server already includes SP1, a cumulative SP2 would have meant a needlessly larger file for Server customers. Finally, in the consumer space the majority of customers have already installed SP1 over WU or will be doing so before SP2, so incorporating SP1 into a cumulative SP2 would take unnecessary time and bandwidth.
