I'm guessing they defined afn because it was frequently useful, then defined rfn because they needed it "for use in macro expansions", and didn't find the refactoring worth their trouble.
Note, by the way, that rfn = "recursive fn" (that's the only reason you would use it instead of fn). But rif is certainly not "recursive if". If you still find it helps you remember it or that it makes more sense, sure, use it, but I would personally use iflet. (Or you could have it defined both ways and use whichever one your brain remembers first.)
