The AK copied the Stg44 in the basic concept, 30 round detachable magazine, intermediate size cartridge, long stroke gas piston, pistol grip, etc. The StG operating system beyond that is completely different.Wasn't the AK born from the STG-44, and proven reliable, and had bajillions of them made? Why not just get an AK?
As far as just buying an AK, I do have several of those. I am a collector and enjoy shooting many varieties of firearms. All shapes and sizes.