You're zeroing in on the actual answer to "why did we replace these awesome high-speed text interfaces with slow GUIs?" Businesses aren't stupid or irrational:

You're zeroing in on the actual answer to "why did we replace these awesome high-speed text interfaces with slow GUIs?" Businesses aren't stupid or irrational: they switched because they moved to an employment model based on a disposable labor force, where workers wouldn't be expected to stick around long enough for training to be worth it, so it was more important to make an interface that was good enough for the endless revolving door of untrained users.