Terracotta tiles were probably more about practicality than astestics as well. There is a good chance that we only find it astetically pleasing because we associate it with historical architecture. If that had been shiny black surfaces we may have thought that modern solar panels look beautiful and antique.
Don't get me wrong, I think it is great to have more choice in what solar panels look like and I think preserving the appearance of historical architecture is important. But I don't think that one is fundamentally more astetically pleasing than the other. It also makes the idea "integrated to the point of invisibility" an interesting concept. What is invisible? Most of our current building are founded in practically with astestic choices a minor customization on top.
Don't get me wrong, I think it is great to have more choice in what solar panels look like and I think preserving the appearance of historical architecture is important. But I don't think that one is fundamentally more astetically pleasing than the other. It also makes the idea "integrated to the point of invisibility" an interesting concept. What is invisible? Most of our current building are founded in practically with astestic choices a minor customization on top.