I'm not sure who originally said it, but I always related to the line "I read a little, but not enough to hurt me none" and it reminds me too of when I took a few piano lessons from a great jazz pianist, I wanted to learn how to play jazz, and he said that the original jazz players had nobody to teach them, and that I should do what they did; invent it. He also taught me the invaluable; 'Never try to play anything that you can't sing.' That one really sunk in.
In learning songs by ear, it is beneficial to know how to hear each note in a chord, those subtleties that give a song flavor, but knowing if it's a B flat major 7th or whatever only becomes useful when working with other musicians-- it's the language that speeds up communication for the players who are all playing a song together.
(Sadly, I couldn't get those videos to play)
Yes I can see that it would be important to be able to read and write music in such circumstances. Perhaps I will learn at a later date, but for now, I don't intend to be playing in or conducting an orchestra, so I am going to stick to the synthesia for the time being.
I do hope to be able to identify tones by sound eventually, and have demonstrated a little potential in this regard by getting a few correct while guessing. But, it is far more often than not that I am get them wrong at this point.. So I know I still have a long way to go.
Eventually the hand's muscle-memory will correspond with the ear's memory of the notes, and where the keys are, relative to each other.
One of the most important lessons that helped me was to practice with a metronome. It forces the hand to learn more quickly in order to keep up with the meter of the song, and improves timekeeping overall.