> Wasn't the main breakthrough its utility and accessibility, not precision?

Utility yes, accessibility no. It quantified the previously artistic. You may enjoy Peter Bernstein’s Against the Gods.

> pit traders were fine pricing different strikes at different vols

Former algorithmic options trader. We ate the former pit traders for breakfast. Modelling the volatility surface is an entire field, and to the extent problems in finance can be solved this is sort of one of them.