With the FX bodies, it doubles as a very good portrait lens. That's where the VR and f/2.8 add value.
The Nikon 105 also works with Nikon teleconverters effectively allowing you more working distance or magnification as the situation requires. The other advantage of a teleconverter is to control your background - either to soften the out of focus area or to line up the subject with a particular background.
In terms of flexibility, the 105mm focal length is nice in that it can be used with extension tubes for more magnification or closer focus, and close up diopters.
The final positive is the 105 packs nicely so I carry it with me even if I have no plans for macro. In contrast, some of the longer macro lenses are a little harder to pack.