I think it's simply that most businesses and investors don't register SQL as having any real problems, and especially now with a resurgent interest in SQL the idea of attempting anything novel feels too risky.
Shameless plug of one recent attempt to offer something different: XTQL https://docs.xtdb.com/intro/what-is-xtql.html
> I would actively avoid utilizing any query language where I have to count brackets
That's really an editor/tooling problem, solvable in many ways, but I guess a Python-like/Parinfer approach would be your preference? (where whitespace/indentation is significant)
SQL actually killed alternatives back in the 80s (and 90s, Postgres used to use a dialect of Ingres's QUEL, the "SQL" bit of PostgreSQL specifically denotes the switch over from QUEL to SQL).