Nice that you appear to feel like me. We both must be over 50 . Poorly behaving guests can spoil the luxury experience and an enforcement of dress code is for the good of all. I know that places like Aman do not enforce anything and this works if all are respectful. Places like Salzburg and Glyndebourne show that you can get people dressed up (at 99 %) by simple social pressure.

Just remember that middle aged fat guy on the verandah at Amangalla with a very unsexy tank top and barefoot (one foot on the coffee table) - I escaped to the pool.

Dress code (and why not restrictions on children) are an essential part of a luxury hotel and definitely make the place being such - period!