Not trying to hijack the thread, but your point about playing with the lightest possible touch hit home.
Unfortunately it was in a bad way. For my first 20+ years of playing, it was in a poorly set up acoustic. So I "learned" to crush the strings. Now I have guitars with great action and I still find myself crushing the neck.
How do I learn to stop?
Get a guitar with super jumbo frets and .007s and play it until you can play it in tune

It has to start as a conscious thought before it can become second nature, so actually focus on your left hand. Play a piece you know by heart so there's no competing for brainpower and start thinking about lifting ever so slightly away from the fretboard as you play.