I dont know the ins and outs of how middleburn manafacture their cranks, but for any new product they'd have to change their setup.
Im sure they've got different setups for square taper, ISIS, 170mm, 175mm, ect.
Im simply saying Middleburn have a reputation for their amazing cranks, and theres clearly trials riders out there that want them to produce a ffw crank......
Im talking about making a product to suit the customers needs. if you want gunmetal grey or white cranks, there's an invention called sandpaper and a spray can