Most people also vastly prefer not having to work on difficult problems. Iverson was clearly trying to provide a notation that would help the (admittedly smaller) group of people who find solving difficult problems interesting and valuable.
John once did a live demo where a negative number (like ¯17.01) suddenly appeared in his APL session log. He looked puzzled for a moment, continued with his demo script for a little while, and arrived at the statement ⎕DL ¯17 (delay negative 17 seconds, and return the actual amount of time waited). He exclaimed "Oh, THAT's what that was!" and continued with his demo.
John had a fantastic sense of humour, if you have not seen them I recommend taking a little time off to watch some of the recordings at https://johnscholes.rip/video/
(btw I second the recommendation of the 1962 A Programming Language)
Edit:
> The third page had an illustration that, in a few short lines, described George Dantzig's simplex algorithm simply and precisely.
> That was the overwhelming, crucial experience.
This is the crucial feature of the APL family for me: they permit algorithm discussions via inline, not block, content.
eg: https://news.ycombinator.com/item?id=28970345
Edit 2: Upon reflection, it's probably also the Achilles' Heel of the APL family: most people vastly prefer easy and DWIMy over simple and precise.