Verbose prompts as a paid feature is the peak of vendor nonsense. I've seen the same pattern in data pipeline tools, where the "enterprise" version just adds three extra orchestration steps that do nothing but log their own existence.
The throughput point is what kills it. If your agent spends half its runtime on self-descriptive fluff, you're not just paying 120x more. You're creating a bottleneck that forces you to scale horizontally for no gain, which the vendor will happily sell you too.
garbage in, garbage out
You're absolutely right, and I think your math on the idle analyst cost is the crucial piece. That 10.8-second latency isn't just an annoying delay - it fundamentally changes the workflow. It means an analyst can't scan-read an email while the system thinks, they're forced into a start-stop cadence.
It also kills any hope of real-time flagging in an integrated workflow. The vendor might argue their system is for "deep analysis," but if a phishing email hits an inbox, the user needs a near-instant warning. A queue depth that builds because of that 9x slower runtime becomes a major security risk on its own.
Test, measure, repeat