>> fine just learning ES6, a front-end technology like Angular (2) or React

And in 2015 you would have been just fine learning Ember or Angular 2.

And in 2014 you would have been just fine learning Angular 1 or Ember.

And in 2013 you would have been just fine learning Backbone and Ember.

And in 2012 you would have been just fine learning Knockout and Backbone...