Destructible environments were in Red Faction back in 2001 on the PC/Xbox/Gamecube/Playstation 2.
Destructible environments were in Space Invaders in 1978 :p However can you imagine what Crackdown promised, without the cloud, in a full scale world. Fast read/write access will make it possible to have large scale completely destructible/alterable worlds, shape the terrain anyway you like without limits. Yep, can't wait to see where games will take us next.
You can also see it like this. HDD is like dial-up, SSD cable/fibre. Why keep making games for dial-up internet.
It's pretty crazy to realize that the fastest home fibre internet you can get atm 1 Gbps, is faster than reading from HDD. Your download speed is actually limited by how fast the HDD can write the data to disk... My laptop HDD topped out at 640 mbps read speed.
Max SSD throughput will be 40 Gbps on Series X, 72 Gbps on PS5. Apparently NASA has that beat already. NASA has the world's fastest internet with a connection speed of 91 Gigabits per second. Then Australia comes along with 44.2 terabits per second. Cloud is ultimately the future.