I go by pubs that state proper attire REQUIRED, no baseball caps and no bare feet, no offensive t-shirts, etc. It has nothing to do with being comfortable with yourself. It has to do with a dress that is what the establishment deems as appropriate and in the spirit of the product on designated evenings. The pretention here is yours, go on your ultra casual line, some of which are more expensive than Celebrity. But coming on Celebrity, a cruise line with formal dress, with your attitude, is crashing the event. And it is all about your attitude and other selfish attitudes like yours.
Establishments can set dress standards just like they can designate smoking areas, have cell phone policies, have age limits, etc. Don't like it, no one is forcing you to use their establishmet.