I agree with much of what has been posted here so far. CCM is NOT an extension of floor medicine. They are very different beasts, and require different ways of thinking.
A sick patient on the floor is usually quite different than a sick patient in the ICU. Granted, many sick floor patients should be in the unit, but long story short, a sick floor patient is not as likely to die as a sick ICU patient.
Also, facility with procedures is not exactly a strong suit of many hospitalists. So, simply adding a year is not the ideal setup. I am not talking about intubations and central lines. More procedures in the way of PA catheters, broncs, trachs, PEGs, etc.
I think it is okay for EM, Surgery, and anesthesia do have to do only one year critical care fellowships--especially since all 3 are very procedure heavy. For most IM docs, however, procedures are few and far in between, even during residency.