Comment by _aavaa_

Go look at videos of the current UI. It's not just doing an alpha blend between two static images. It's doing real time effects to mimic refraction and color separation the way you except to see through glass.

Also, 20 years ago you're talking about desktops connected to the wall, or laptops with no expectations of battery life. The name of the game for phones is use the hardware as little as possible a down clock asap. The fancier the UI, the longer older hardware need to stay upclocked and the more they have to work to hit 60fps (or more) smoothly.