I think it's a packing issue, more than anything. I generally do bring a sports jacket or 2 on vacation.. But for example, our next cruise is Alaska, and it's going to be 10 nights. So instead of mostly packing shorts and t-shirts for just 7 nights... It's 10 days of packing, it's a lot of "layers" for Alaska. Having to also bring extra "nice" clothes... it's just a matter of space in the already stuffed suitcase.
Plus of course... Different people have different perspective about dressing up. Some people never dress up for their jobs, and feel totally uncomfortable doing so. Other people may never dress up for their jobs, but look at a Palo meal as a "special opportunity" to dress up. For people who do wear suits to work every day, some of those people might look at vacation as the opportunity to get out of their suit, while others may be perfectly comfortable wearing a suit all the time and feel naked without a collar and tie.
Finally, it's a matter of how people look at the experience. If someone looks at a meal as Palo as being a super special occasion experience, versus someone who might look at brunch there as being about equivalent to a good Olive Garden meal.
So I think it comes down to those a few issues: A question of an overpacked suitcase, and a more personal question of what attire you feel comfortable in, and finally how you look at the experience.