Awesome pictures by and awesome artist. The Luminous School was fantastic and proof that American artists are or were as good as any in the 19th century at any rate.
For the most part I agree with you, but as a HUGE fan of the Pre-Raphaelites, I'd contend that movement only could have started in Europe under the protective wing of Ruskin.
My Senior Thesis for my Art History BA was on Cole's Voyage of Life. I spent many hours in the National Gallery, completely engrossed in those paintings, and indeed, they are amazing.