The reason for all this, despite the "man, js is terrible / slow" argument, is just that there are a lot of web-developers out there, with a big bag of tools, frameworks and "to-js"-compilers, wanting to create something, but just don't have the time to learn a complete new cross-plattform infrastructure, which JUST DOESNT REALLY EXISTS. You have to ponder if its just worth the efforts to build something native or go fast(in terms of development-time) and cross-plattform with sometimes reasonable trade-offs.

If there will be a "mostly unified" UI-Framework for android,ios,win10-mobile,windows, osx and linux for any compiled language, i will be the first to jump onto that waggon...