Why are lip lifts not common and advised against?

My upper lip sits too low on my face and when I speak my upper teeth don't show because my upper lip covers them completely. I would love a lip lift to show a bit of my teeth when I speak and to help balance out my face, however many surgeons told me not to because it causes major scarring. Is there any other major complications, such as nerve/muscle damage? I have had rhinoplasty, would the incision cause nasal swelling as it does with rhinoplasty? Do I have to dissolve lip filler first?