As a long-time owner and frequent professional gigger of a Sadowsky NYC (as well as several other J-style basses costing over $4k), I agree that there are no *material* improvements.
As to why someone would pay that, it's none of your concern. is it worth it to me? It's different, and much lighter than my other basses and I can afford it... so yeah. Better? Subjective. Better empirically, than say my '74 J that's beat to hell? No. Both sound great, both play great, both stay in tune. Nothing else maters materially. The passive Fender is probably more reliable just inherently because it has no preamp. That's just reality. Regardless, I do what I want and others shouldn't worry about it just like they shouldn't believe in magic or hype.