Backend developer here.
Everytime I need to create some sort of rich UI I discovered that the last framework I learnt was "no longer valid". Happened with JQuery, Knockout and now Angular 1.
My feeling is that frontend development is overcomplicated/overbloated. Specially with the big players (Angular, React). Lucky me, I found my way with riot.js. Simple, elegant, lightweight and fast enough. You don't need a lot of complicated boilerplate, nor learning a new template language or syntax.