Retrograde?

My thesis explores 20th century revival textile design, and as part of this project I am studying the Art-In-Trades Club of New York, which was active during the first half of the century. This organization endorsed the use of museum collections (specifically those at the Met) in industrial design. Its members believed the motto of the American designer should be "the old in the new," and their exhibitions during the 1920s championed period styles.

I have been reading both primary and secondary literature related to this topic, and I'm having a difficult time with both standard design history and scholarly discussion of what was Modern, with a capital M. Period style, in comparison to Modernism, is still viewed as retrograde, but even modern objects have elements of historicism, some glaring.

As food for thought (or eye candy?) I'm including an example of wallpaper, which I will talk about next time. Guess when this dates from?