Modernism -- i.e., the Bauhaus, the International Style, and Le Corbusier -- was always about big, cheap, and ugly. The Amsterdam School was Expressionist, not Modernist; and nothing's more anti-Modernist than a pretty painting on a wall, even if it's in a visually arresting 1930s style.

But that said, the Amsterdam School and the WPA work were beautiful, and I'd never heard of them before. Thank you for mentioning them! I'll be sure to look into both in a lot more detail.