Nope, I still don't see the logic.
Microsoft has woken up to the fact that they don't need to pay for things like Dolby Digital Pro licenses in Windows 8, so they are moving to charging users for the Media Pack, which they make available to the enthusiasts, who, by Microsoft's thinking, are the ones using Windows 8 Pro.
Microsoft is currently paying for licenses unnecessarily in every copy of Windows 7 Home Premium and up. It makes perfect sense for them to turn WMC into a paid for Add-on. Why should they throw good money away?