Being pale is still desirable for the middle class themselves, though, as they're trying to avoid being seen as lower class (tradespeople, farmers, etc).

Also, thinness is actually a middle-class obsession, because it's the lower class who "don't have enough free time to go to the gym or take vacations in warm places." The upper class don't care what their bodies look like, as they all know that they and everyone else in the upper class can afford to "throw money at the problem" (plastic surgery et al), and so how healthy you look is no longer a good signal for how healthy you actually are. (Instead, they tend to judge your genetic fitness — when they care about that sort of thing — by the health of your lineage, going back several generations. Which is one reason royals/nobles make a big deal of keeping track of that.)