Goes without saying.
FWIW the Pollen file extensions are not purely cosmetic. The Pollen renderer consumes Pollen source files and uses the extension (pm, pmd, pp, etc) to determine what kind of rendering is necessary. Of course this could be signaled from within the source file, but then I'd have the bootstrapping cost of having to load a file to find out how to render it, and then reload it to do the actual rendering. Whereas reading a file extension is simple and cheap.