Don't let the marketing people be program managers. No offense, but I think my readers will agree that good marketing people rarely have a good enough grasp of the technology issues to design products.

Basically, program management is a separate career path. All program managers need to be very technical, but they don't have to be good coders.  Program managers study UI, meet customers, and write specs . They need to get along with a wide variety of people -- from "moron" customers, to irritating hermit programmers who come to work in Star Trek uniforms, to pompous sales guys in $2000 suits. In some ways, program managers are the glue of software teams. Charisma is crucial.