The most interesting thing about AI rewrite stories isn't the time saved — it's the forcing function. Someone had to articulate what the system actually does clearly enough for an AI to replicate it. That clarity exercise alone often reveals the architectural problems that caused the cost bloat.

The $500K/year wasn't from JSONata being expensive. It was from an architecture that serialized, sent over the network, and deserialized for every expression evaluation. An engineer documenting that flow for any reason — AI rewrite or not — would likely have spotted the problem.