In my experience the smartest people don't want to work on UI's, which is probably the reason they are bad. The smartest go work on other parts of the stack, doing things like machine learning or infrastructure.
The only place where you have the smartest people making UI's are in games, they often have very impressive performance and functionality. But even in games people hate making UI's, it is just that in games people care about the product so they bite the bullet and do it themselves.
Note that I am not saying that UI is easy or unimportant, making UI's is both hard and super important which is why it is a huge problem that we can't find good people for it.
The only place where you have the smartest people making UI's are in games, they often have very impressive performance and functionality. But even in games people hate making UI's, it is just that in games people care about the product so they bite the bullet and do it themselves.
Note that I am not saying that UI is easy or unimportant, making UI's is both hard and super important which is why it is a huge problem that we can't find good people for it.