I had a feeling that there used to be a lot of Alpine maps in development, especially payload, but i have absolutely zero evidence!
I agree with Muffin Man, Alpine Maps are ugly, and so is lumberyard (well its the best someone could make out of it). The problem is not the theme itself but the color scheme / grass textures.. Saturated green just doesn't fit with the red textured classes and especially not with red buildings. Even Brown (/wood) doesnt seem to fit.
having red blu and green at the same time doesn't fit tf2s idea of impressionistic art direction and simplicity. it may work with brownish-green grass, but that wouldnt fit the alpine theme, maybe a mediterranean or south-american map. idk.