If they wore a properly fitting , somewhat traditionally correct tux, most people look great in tuxedos.
That kind of tailoring with the 1 button and some type of waist covering is fairly universally flattering when done right. It does seem a bit weird that everyone dresses the same but there's a bit of charm in uniform when done right.
Also, there's nothing wrong with doing something because of a sense of tradition and formality, that's just culture. It's also about respecting those traditions which may still mean things to people.