Quote - Can you point to some examples of HR2 files that are really just hair files (i.e., not figure cr2 files that were placed into the hair library with the file extension changes from cr2 to hr2) and act differently than a hair figure (cr2 file) just parented to the head?  I'm asking because real hr2 files should act just like a parented cr2 file when posing the parent figure.

Yes, mine. An HR2 file is a derivative of the Poser prop (PP2) file, except that it should automatically smart parent to the selected figure's head, and if there is hair already parented it will remove it.

 To answer the original question, though: HR2s are easier to make*, and easier to use, except in the case of long hair - that is, hair which is longer than collar length or thereabouts. Rigging long hair is the simplest way to make it work. The alternative is to make an awful lot of morphs, which is frustrating both for the creator and the user. I can't speak for others, but that's the reason for me.

*How to make an HR2 hair: position the hair mesh on a (preferably) zeroed figure, parent to the head, save to the hair library. Simples. :)