1. I'd have to add about corsets though that it was taken to debilitating extremes.
A thing that was also common in the 18'th century was "fainting rooms" which were exactly what it sounds like. The compression severely limited blood flow and even the ability to breath, so there was only so much moving around you could do at a party in between going to lie down because otherwise you _will_ faint and they'll drag you there.
Another thing that was also common were smelling salts to revive a fainted lady. Yes, it was actually that common that corseted women would faint, that almost everyone in the upper classes carried some.
I'd hardly think of it as some ideal to copy, basically.
2. It being common in the 1800 is mostly explainable actually, like most things fashion, by a neverending quest to make it clear that one doesn't do any physical labour. Clothes, looks, you name it, at least half of it was humanity's quest for a status look that says "look at me, I'm a useless piece of furniture and can afford to be one." (While at the same time preaching protestant work ethics, where applicable.)
Take the tan for example. As long as most work happened outside, humanity had a quest to look as pale as possible, to make a point that one isn't one of those unwashed peasants working in the fields. People even ruined their health with arsenic-based potions to look properly upper-class paper-white. (ETA: and as you would guess "Snow White" actually meant she was an ideal of upper class beauty, as well as a true upper-class lady.) Then as in the 20'th century most jobs moved indoors, suddenly it was fashionable to sport a tan, to make a case that one can afford going to the beach.
Or take breasts. Actually from antiquity to the Victorian era, all the rage were small breasts, as most women would be pregnant or lactating half the time and big breasts tended to be the norm. Small breasts said "young and virginal" or, again, "stinking rich and can afford a wet nurse." Then in modern days as people started postponing making children, all the rage became what previously was mundane.
Waists are largely the same. As long as it was an economy of shortages and even knights often had to plough the land to make ends meet, being fat was something good and sexy. It meant not just that you probably will survive the next famine, but also basically that you can afford it. Status symbol looks all over again. Then at some point it flipped around, with corsets and crinolines (which made the same impression of a narrower waist by comparison) making a point that basically (A) you're so well off that you're not worried about the next famine, and (B) basically being an outfit so disabling that you definitely aren't one of those who have to do any work any time soon.
What I'm getting at, and why I included the other two examples, is that you really can't take it as some indication of built-in human tastes. Just about any element of body shape or hue -- waist, breasts, feet (see the Chinese), you name it -- just flips around with basically whatever is the fashion du jour.
3. What I'm also getting at, is that at least back in those days it served a purpose of making an "I'm rich" case. Whereas the mutants in these photoshopped pictures, well, I'm at a loss what that would say. "My parents spent a vacation at Hiroshima" maybe?
