Just as the 2X12 cab design, the other guitar speaker cabinet on this site, the 4X12 is a ground up redesign of rock and roll. The 4X12 is as rock and roll as sex and drugs. Many guitar heroes were born, some using one 4X12 and some using a wall of them. Anyone wanting to blow the walls down in their garage with their friends coveted a half stack.
I always wanted a Marshall half stack and eventually bought one. It was dragged all over the place to jam spaces and gigs, it worked and never gave me any problems. After years of faithful service it was sold. I simply did not need something so big and certainly did not want to move it around. This led me to design a 2X12 speaker cabinet. I wanted the sound of a 4X12 but less size and weight. Some people still want big stupid rock and roll, enter the 4X12.