Why do we constantly change this? What technological advance was not available x years ago to dream up usb 4? We already know we will use the bandwith, why no

Why do we constantly change this? What technological advance was not available x years ago to dream up usb 4? We already know we will use the bandwith, why not dream up what will be the usb 8 spec in 20 years now and have everything working without change for 20 years?