So the approach is: make the UI first, make it fast, and then wrap an API around whatever evolved. A controversial methodology, but given the imperative for making a responsive UI, it makes sense.
However good this approach is for creating fast UIs, it's death for feature development and fast responsive innovation. With an API you can develop in parallel and release stuff faster and iterate faster.
身邊一些技術背景的朋友，對 API 遲遲未能開放，看不到各式各樣 APP 的狀況，都是持負面看法的，所以上述疑問是很多人共同的看法吧。