Windows 8 Professional x64 RTM does have WMC on it, but had to use another product key for WMC to enabled addition features, it rather stupid from Microsoft to disabled WMC and have to purchase option for WMC. Rip off.
No
It's better to have it as an optional extra. It drives the price of the OS down. MS have to pay for licensing costs for DVD playback etc
Personally, I only ever want WMC on one pc in the house. So if Windows is cheaper for the rest of the machines, that works out well for me!