hmmm. the chin just seems like an essential feature, im not sure if an advanced jaw can still create the effect of a stronger chin. also, i think the real difference is gender, females tend to have softer tissue than men and a lot of showcased AG are female.
This is a very interesting thread and I have several observations to make.
For people with retrusive lower jaws (i.e. a weak looking jaw but perhaps no MAJOR functional problem, i.e. a class 1 or 2 occlusion) I have personally consulted with some maxillofacial surgeons and cosmetic surgeons who have suggested that a simple genioplasty would solve my cosmetic problems. In some cases the surgeon suggested a genioplasty with some grafting of bone from the hip to fill out the space. This produces the benefit NOT ONLY OF STRENGTHENING THE CHIN, but a genioplasty when advanced can also lengthen the appearance of the jawline itself.
Another advantage of a genioplasty(over a chin implant for example) is that not only can you project more horizontally with a genioplasty, but you can also vertically lengthen the chin through a genioplasty. If you go over to the "makemeheal" forums which are primarily devoted to cosmetic sugery you will find under "genioplasty" examples of several patients who have benefitted comsetically from genioplasty and they look really good, in some cases much better than patients who have had jaw surgery.
Clearly, this has to do with the the fact that they had their genioplasties performed by cosmetic surgeons(trained in the procedure) who were primarily concerned with aesthetics (genioplasties serve little to no functional benefits). In fact, the ps I consulted with(he was also a craniofacial surgeon and was trained in doing jaw surgery too) actually drew out on a piece of paper what he said was the "most attractive" chin shape on most people society calls "pretty boys". I got a good chuckle out of that, but he was actually right when I looked at magazines afterwards. It was a somewhat protrusive chin with a soft curve and now I see it in the profiles of most male models. Apparently he said he could create that chin through a sliding genioplasty and intergrafting a bit of bone or bone filler into the gap. I've seen some of his after results and they were pretty awesome(on both men and women). His chin advancements were sometimes close to 15mm --and he never indicated anything about problems with this...though I haven't done a long term follow up on his patients.
It seems to me that if a genioplasty can indeed improve or help the cosmetic outcome of a jaw surgery it should be done. Also, it seems Arnett and Gunson are some of the most advancement surgeons in terms of using grafts etc. so hopefully they can create the same types of effects as the surgeon I consulted with. I guess you probably just have to ask.