The 1/0 thing confused me for a while because 0 looks like a circuit (on), and 1 doesn't (0ff). I was also taking electrical engineering classes at the time, and the 1/0 true/false thing was already halfway arbitrary because of active-low pins, and even in software land, "return 0" could mean either true or false depending on the context.
I agree that I/O has always been confusing and non-intuitive. O stands for "On"? For "Off"? I means eyes-shut? O means eyes open?
The new symbols aren't any better but the UX of "push this button to turn on or off" combined with obvious lights/etc when something is on has mostly made the semantic meaning of the symbols obsolete to 99% of consumers.
The difference between perfect circle, 'o', 'O' and '0' is contextual, since the shape of all four of them is approximately the same. On their own, the characters themselves are often ambiguous in print, and totally ambiguous in handwriting.
