Obviously wrong. America has an enormous amount of beautiful "old" architecture. Most streetcar suburbs are shockingly beautiful, from the utilitarian carriage houses all the way up to the mansions and large public buildings. It all predates WW1. The reason truly is psychological. At the elite level (public institutions, taste makers), it was an infatuation with European iconoclasts wrapped up in an anti-establishment fervor after WW1.
Ironically, it's the unenlightened idiots in America that clung/cling most to archaic, conventional notions of beauty and comfort.