Agreed. These maps were excellent. My guess is, once they've patched in all the original Cod4 maps this December, they'll probably make the Variety Pack available later as paid DLC.
Or, if Activision really wanted to be cruel, they'd attach just one Variety Map to each Infinite Warfare DLC. Basically meaning you'd have to buy all the Infinite Warfare DLCs or the IW Season Pass in order to get all 4 of the Variety Maps. Sounds gratuitous, but with the way they're selling MWR in the first place, I wouldn't put it past them!