alt Hacker NewsI don't really say this to disagree with you, but I feel weird about the phrasing "found insufficient", as if we reevaluated and said 'oops'.
It's not like 5-bit codes forgot about numbers and 80% of punctuation, or like 6-bit codes forgot about having upper and lower case letters. They were clearly 'insufficient' for general text even as the tradeoff was being made, it's just that each bit cost so much we did it anyway.
The obvious baseline by the time we were putting text into computers was to match a typewriter. That was easy to see coming. And the symbols on a typewriter take 7 bits to encode.
Also, statefullness. Baudot has two codes used for switching into one of two modes: figures and letters.
Typewriters have some statefullness, too, like "shift lock". Baudot needed to encode the actions of a type writer to control it, not the output.