> I'm probably failing to consider edge cases but it seems like a potentially simple tweak that might make lisps more palatable to many
Lisp came out in 1960. The s-expression-only syntax was an accident or a discovery - depending on one's view. Over the many years no attempt to add significant indentation syntax without parentheses gained more than a few users. Syntax variants without parentheses (and no significant indentation) only had a marginally better fate. Sometimes it even contributed to the failure of Lisp derived languages (-> Lisp 2, Dylan)...
Lisp came out in 1960. The s-expression-only syntax was an accident or a discovery - depending on one's view. Over the many years no attempt to add significant indentation syntax without parentheses gained more than a few users. Syntax variants without parentheses (and no significant indentation) only had a marginally better fate. Sometimes it even contributed to the failure of Lisp derived languages (-> Lisp 2, Dylan)...