The problem with normal flashguns is the means you have to use to attach them to the camera if you're on the go, which can run the gamut from the creative to the cumbersome and frustrating and effectively ineffective in the field. A ring flash such as this one would make it easier to take photographs of skittish insects whilst allowing you to shoot at lower ISOs for best image quality; not to mention that a ring flash fits comfortably on the lens and, aside from possibly preventing the use of a circular polariser, allows for greater mobility and ease of use.
I dont really agree (not to put your viewpoint down, or imply it is incorrect). All it takes is a bracket and an off camera flash cord. Its not as elegant or streamlined, but its hardly a problem, especially considering the dual head MT-24 that is the bee's knee's for macro.