No, but there are cases where you already have something suitable as PRK, so you can skip the IKM -> PRK step; see section 3.3 of the RFC (http://tools.ietf.org/html/rfc5869). This is a use case for me actually; my "IKM" is a bunch of CSPRNG output, so it'd be fine to skip the first step. (It also wouldn't hurt, FWIW.)

In most cases you do want both steps, and as you said, making people do it themselves is kind of dumb, so perhaps we could have a convenience function that just calls the two steps separately.