Years ago, when I asked my dentist about getting veneers to fix my weak smile, he said "first you'll need surgery to move your lower jaw back". I thought he was nuts and did not raise it again. Now I understand he meant that any veneers would get sheared off due to my underbite.
I saw a bunch of orthodontists earlier this year. All said surgery within a minute of seeing me. The first surgeon I saw said you've got an 8 mm gap there, so the upper jaw should be moved 6 mm forward, the lower 4 mm back. The other 2 said they don't see such a gap ("but you can't really make an exact surgery plan before the teeth are more or less straight), and I will probably manage with the just the upper jaw getting moved forward*. (My upper teeth just scraped the lower ones pre-braces).
When I told my dentist about maxillary advancement being the primary (if not the only) surgery being proposed, he said that since I have a sloping profile, he would have thought that moving the lower jaw back would have been aesthetically better and "maybe upper jaw surgery is an easier operation for them".
*I've had braces for less than 2 months and only on my lower teeth, and the top and bottom teeth already no longer touch at the front. Maybe the single-jaw theory was just to get me to commit to treatment.
EDIT: Forgot to add. One of the orthos I saw was very cool on the whole idea. "Surgery has minimal effect on how your teeth and face looks. Your bite is good enough. You can bite a hair! So you'll spend all this money to look different, not better, but different. If you haven't had any functional issues so far (36), you are unlikely to develop them." The surgeon that works with him has a very good reputation. One of his patients is one of the best looking underbite cases on youtube. He told me that the difference would be slight, positive and definitely noticeable to myself. I was happy with this consult, but since the ortho was so unenthusiastic, I went elsewhere... To the surgeon that trained that surgeon. (That's how it is in Melbourne. Every ortho pairs up with one or two surgeons and vice versa, and you can't mix and match them. Which, I suppose, makes sense from a case management point of view. ie. every surgeon and ortho can discuss all their cases once a month instead of scheduling multiple appointments.)