No, I write a proper RPM spec file - only takes a few minutes.
So, what's the added bonus of using setuptools then?
setuptools is just less generally crufty than distutils, and things like entrypoints make writing installable console scripts feasible. Since it provides essentially the same interface the default rpmspec created by rpmdev-newspec works with it out of the box.
Also, I assume you're talking about the bdist_rpm target that come from distutils.