People do need to write UIs in C++ though (sometimes as frontends for some of the purposes you mentioned), and Qt is probably the most used UI toolkit for C++.
Wt is basically Qt for the web. I've used a lot of UI toolkits across many languages, and Qt with modern-ish C++ is fairly productive, doubly so if you're slapping something together for an existing C++ codebase you have.
This is the exact use-case where I've used Wt. Existing C++ codebase, needs an admin interface, needs to be accessible over the corporate intranet. Wt is perfect for that.
I've written several applications using this approach lately, administrative systems.
None in C++ yet, but Java & Go.
Integrating the UI tightly with the backend has a lot of advantages and I strongly prefer working in a sane language to both template engines and JSON APIs.
Wt is basically Qt for the web. I've used a lot of UI toolkits across many languages, and Qt with modern-ish C++ is fairly productive, doubly so if you're slapping something together for an existing C++ codebase you have.