I think it's because most surgeons and orthodontists focus on making the bite perfect instead of making someone's face look better; in fact, both braces and jaw surgery were developed for that and not for making people better looking. I read a few studies where they asked the opinion of orthodontists and lay people on how people looked (for example, before and after jaw surgery or with different degrees of gum show) and often there was a statistically significant difference between the two groups; i.e. what most lay people thought looked good was different from what most orthodontists thought looked good.
Also, it's interesting that Invisalign was not invented by orthodontists but by a random guy with no medical background that happened to be an adult orthodontic patient. Orthodontists just can't see what's wrong with having your mouth full of metal for years and years. I am a middle aged woman and I have to regularly speak and present in front of people as part of my work, I have severe lip incompetence etc. so my teeth are always on show and the orthos I spoke to recently could not understand why I did not want to wear traditional metal braces for years - they gave the impression I was fussy and one literally said nobody would notice the braces
. I'm sure they're trying to help patients but they just have a different perspective, at least that's been my experience.