Programming is no more a creative field than other branches of engineering or the sciences--and in fact many white collar professional jobs. The sort of exceptionalism that gets attached to software is pretty ridiculous.

And yes there are agencies and consultants for all sorts of specialized work on a project basis. But that's not the majority of software and I'd guess the majority of programmers/software engineers don't want to be constantly looking for work especially if demand lets up.

Obviously, some things like games lend themselves to more of a project-based approach to staffing than other things do. (And certain other engineering projects do as well.)