Design without purpose or function is just art and I love and appreciate art. I enjoy the details, the beauty and creative expression of it. But if your reason for making something beautiful(an app or a product) is just for the sake of making it beautiful; then its not really design. You are right about the fact that aesthic beauty and function can co-exist. A well designed product can perform its function without being beautiful but it never works the other way round. The term “Well designed” has little to do with beauty. This is where your article misrepresents ‘Design’.
The reason art/beauty and creative expression exists is because its completely free or devoid of function and has a realm of its own. It’s beyond ‘design’ per se so that artists have complete creative freedom to go beyond the boundaries of function and create.
Design will always be about function and aesthetic beauty will continue to compliment it.