This thread makes me wonder about the influences in people's lives when it comes to appearance. My mom LOVES to be comfortable, but she dresses nicely for work. My dad, and his family, tend to be more vain/image conscious and he would often do his clothes shopping in button down and tie when I was a kid. "When you dress nicely, people treat you better," he taught me. Maybe that's not how it should be, but I think it's generally true. I love to dress for dinner. I see both sides: 1. I paid so much for this vacation I should get to do what I want; and 2. I paid so much for this vacation, my vacation deserves me dressing up (this shows my family/traveling companions and the staff of the ship/resort that I value their time/effort/money they spent). I will always fall in the second category, while my husband who always wants to wear jeans is closer to the middle but dresses up more for me.
As for the future, I hope the pendulum will swing back towards more dressy, but I doubt it. I think so much depends on how the next generation is taught to think about appearance, self entitlement, and respect for others. I will try to teach my family what I value about dressing/looking well, but others will teach the opposite. This doesn't guarantee either my kids or theirs will agree with us.
Btw, for the record, I'm early 30s, so I don't know that this is just age/generation based. I really believe it's a culturally learned value, both macro and micro.