I never suggested that I was the first person to think of this; not having dealt with any Lisp since (hmmm) 1990 via Scheme in my introductory CS 212 class at Cornell probably has something to do with my ignorance of the prior art in this area. I do like your approach of breadcrumbing me instead of giving me the answer, though... best I can guess is "tooling" and simply that S-expressions are simply too embedded in the minds of the Lisp community at this (or previous) point(s).
I also don't deal with significant-indentation in languages usually (and have a strong Python distaste); though I've been playing with Roc (https://www.roc-lang.org/), which has this, and have used HAML (https://haml.info/) in the past, where it seemed useful. I suppose auto-indenting is impossible in a significant-indentation language depending on what the editor can intuit based on how the previous line ended, but I don't think I'd need that feature as long as it simply held the current indentation and just let me hit Tab or Backspace. (I could see things becoming a mess if you manage to screw up the indentation, though.)
I did research "sweet expressions" (which are apparently also called T-expressions) and found the prior art there in Scheme and Lisp, and a library called "sweet" for Racket (which is another intriguing lisp dialect!). These might have gotchas, but apparently they've sufficiently solved the problem enough to be usable.
I do simply like how "T-expressions" look. Which is something I guess I care about, although I know that's not a universal among coders. (My guess is that those who care about such things are simply not 100% left-brained about their coding and are invested in the "writing" aspect of the craft.)
I also don't deal with significant-indentation in languages usually (and have a strong Python distaste); though I've been playing with Roc (https://www.roc-lang.org/), which has this, and have used HAML (https://haml.info/) in the past, where it seemed useful. I suppose auto-indenting is impossible in a significant-indentation language depending on what the editor can intuit based on how the previous line ended, but I don't think I'd need that feature as long as it simply held the current indentation and just let me hit Tab or Backspace. (I could see things becoming a mess if you manage to screw up the indentation, though.)
I did research "sweet expressions" (which are apparently also called T-expressions) and found the prior art there in Scheme and Lisp, and a library called "sweet" for Racket (which is another intriguing lisp dialect!). These might have gotchas, but apparently they've sufficiently solved the problem enough to be usable.
I do simply like how "T-expressions" look. Which is something I guess I care about, although I know that's not a universal among coders. (My guess is that those who care about such things are simply not 100% left-brained about their coding and are invested in the "writing" aspect of the craft.)