In the 1920/30s dress-shirts in fine linen were the height of daytime elegance. It would not have been the coarse linen used today for casual shirts, but the finest semi-sheer handkerchief linen.
I have read in a number of sources that a lot of things went out of fashion as the world, for lack of a better term, "democritized." Â The theory goes that back in the day when domestic help was much cheaper to hire, because the class structure was more rigid and opportunities for those at or near the bottom much fewer (to say nothing of other reasons), the upper classes were much more willing to wear things that were hard to maintain because, obviously, they weren't the ones who had to worry about maintenance. Â It was a sign of wealth to wear light colors and such, things that had to be washed all the time. Â Hence, for instance, Gatsby's pink suit.