So if my bank didn't use JS, the already drawn out processes would take even longer. Transfers would require more clicks, more full page reloads. No benefit to

So if my bank didn't use JS, the already drawn out processes would take even longer. Transfers would require more clicks, more full page reloads. No benefit to the user. In fact, the opposite. The user just feels their banking system is even older and more outdated. So your use of "not necessary" is rather debatable and probably not the same as the PM's. As far as security on the API, I'm not convinced. Don't use cookies for authentication -- is that a big problem?