It's not regression. It's progression. Power users are more efficient and proficient on what you (incorrectly) refer to as 70s-styled terminals. It took us a while to get there. We went down the wrong path with fancy GUIs in the 90s, 00s. Things like not needing a mouse, being able to freely tie programs/commands together, being able to script every aspect of your workflow,... these are all big wins for power users. If there is an easy way to achieve the same flexibility with GUIs, then it hasn't been discovered yet.