So, I would have fully expected this setup to be 2 primary partitions. Not sure why MS doing this would have made anybodies life more difficult.
In many OEM installations, you have 4 primaries out of the box (100MB, C, Recovery and tools). If you then want to create more partitions, you have a problem. Many people not familiar with the NTFS restrictions go ahaead and run into the dreaded dynamics.
We had a lot of examples of this problem and it could be avoided if MS and the OEMs used the primary partitions more sparingly.