While I agree with your point that computers should do the most they can to take the work out of things for the user, the flight search example used in the article is exactly the sort of thing that at some point you're likely to need to input. It's a plan that the user has that they want to action. While you could use voice recognition or call a person to do the same, some people are probably going to want to type it into a flight search or calendar app or similar, so the GUI for that is necessary.
"Making rounded corners and gradients is easier than making something useful. that's why it gets so much attention"
It's not about it being easier, it's about making it obvious that the user can use it. Following established design conventions for buttons by gradating backgrounds or rounding borders, however right or wrong they may be, can help a user to know the intention behind something without needing to think about it.
Look at the last frame, "Title Your Guide". The website/app doesn't provide it's own keyboard wudgut. Why the fuck does it have 3 wudguts to enter a date?
"Making rounded corners and gradients is easier than making something useful. that's why it gets so much attention"
It's not about it being easier, it's about making it obvious that the user can use it. Following established design conventions for buttons by gradating backgrounds or rounding borders, however right or wrong they may be, can help a user to know the intention behind something without needing to think about it.