Well, implementing basic UI functionality even is hard enough with all the changing environments, screen sizes, rotations, touch interfaces and what have you. M

Well, implementing basic UI functionality even is hard enough with all the changing environments, screen sizes, rotations, touch interfaces and what have you. Making it as simple as possible makes it possible to focus in making those work in a more functional and usable manner. While it is true that CPU and GPU powers have increased, also the ways we use our machines have changed, people might have wildly different environments that the same UI needs to work on these days. Scalable UI alone can become a nightmare if you have anything more complex going on. Even the big players have a hard time figuring out proper usability, like look at Apple or Microsoft constantly making a hurdle to iterate on their designs, making mistakes along different releases. Building usable UI is freaking hard and requires a lot of user feedback, iteration and focusing on details that you don't know before starting to build the product. Changing even one thing can lead to another thing breakin, and so on..