From a marketing perspective
From a marketing perspective it makes total sense because they are now coming out with the Mach E that they have tied to the Mustang. And then to have a specialty Mustang clock in below the Shelby models but above the GT, Mach 1 is a solid name. For the new Bullitt they added the iconic green paint and torque trust wheels and some other trim bits, plus an extra 20HP. Hopefully the Mach 1 will be more than an appearance package.