A wild guess: more computing power means more content that can be processed and the need for more content can be addressed by computer generation. For example, just a few years ago open world games were just a handful and required a lot of work. Nowadays even a simple game can have a large procedurally generated world.
Adding to this, more computing power at everyones desk. Very good computers were probably capable of generating good maps five years ago, but if everyone can play around with generators and models as a weekend project there is a lot more innovation and development!
