Orthodontics for jaw surgery prep and orthodontics by itself are two different things.
After tooth extractions, the ortho will pull the non-extracted teeth back toward the molars and retract your jaws into your face. If you get surgery, the surgeon then moves your jaws back out and into correct position (i.e. looks good). If not, your jaw stays retracted and the ortho tips your teeth to try to cover up your bad bite... but you can't hide bad bone structure, only bad teeth (i.e. looks horrible).
If you can avoid tooth extractions altogether as prep for surgery, I think that's the best scenario. But if your arches won't support it, that means extractions or arch expansion, which adds cost and other potential issues if even an option.
