In other words, people would rather make many tiny, seemingly easy steps than a few really impactful but seemingly arduous steps.

Teach SQL a spoonful at a time then, I suppose. Do not start from having the students to read Codd's original papers.

OTOH SQL is not the best language: it's both too wordy and too terse, it's not composable in many important cases, it does not map nicely to set-theoretic operations. But a transpiler to SQL that would offer a vastly better experience is yet to take the world by storm.