I'm guessing that you and your DH are pretty slim people, since you don't understand the talk about chafing and since even just your foot bones can handle wearing jellies and kitten heels. (Ok the shoe part doesn't include DH, LOL) And I assume that nature or perhaps where you are from allows you to wear nicer clothes without totally sweating through them.
That's not many people. I might have lost some weight and now don't have to worry about chafing (though there are plenty of smaller people who still do chafe...just the nature of how an individual's body is put together!) but I have always been a "sweater", so I'm not going to wear a nice dress, etc, for a full day in the park.
I now tend to wear simple shorts from Old Navy (not workout shorts...I wouldn't wear these shorts to the gym), my nice running shoes (I don't understand how wearing those shoes makes me look bad?), wicking socks, and a simple shirt. I do tend towards really "loud" colors, which isn't everyone's style, but the clothes themselves don't look bad.
But I, by the end of the day, don't look awesome. I'm not generally posing for pictures at the end of a long, sweaty, day.
Also know that wicking underclothes don't come in unlimited sizes. Before my WW success I wouldn't have known where to find them, and wouldn't have wanted to buy them. So the days that I did wear a sundress I was also wearing some sort of normal shorts, which didn't help the heat or chafing at all.
I think that your feelings are very much a product of your own personal body-type, and I think it's nice to put ourselves into the shoes of other people, and it can help us be more understanding as to why some people aren't dressing the way you want to dress.
And remember that in the early days of, especially,
Disneyland, people weren't spending 10-12 hours in the parks. It was a few hours and then home/hotel.
By the way, you should check out Dapper Days out at Disneyland. Might be something you would really enjoy!