JavaScript fatigue is real
JavaScript frameworks seem to come out every 12 minutes. The first debate they go through is "It is a library not a framework". The next debate they go through is, "It is not a robust as (Angular, React, Ember...)". The final hurdle they have to go through is GitHub stars and adoption.
All of that being said, I'm tired. Actually brain tired... I have learned JavaScript, jQuery, jQueryUI, MooTools, YUI, ExtJS, Knockout, Backbone, KendoUI, Angular (barely), React, and currently using Vue.js
That is a lot of stuff to learn... and remember... and apply... and.. you get the point. My point in all of this is simple, you will become tired of learning Yet-Another-JavaScript-Framework. You will hit a wall. You will wonder "Why is this one the latest flavor?". You may squash that quickly with, "I just gotta get it done".
DO NOT STOP QUESTIONING!
Those questions that you have are real. They make you a better a developer. Ask, WHY! Why should I learn Angular 2? More often than not the answer will be simple, "that is the framework we went with before you got here". That answer is often followed up with, "Can we change that to (your framework here)?". Make sure you have specific reasons for that and you will be surprised. You should always have a questioning mind about why you are doing something.
DO NOT STOP LEARNING!
That seems to go against the original comments of this post, but actually it will allow you stop going deep into languages/frameworks that you may not need to learn. You need to learn enough about something to understand why it is good or not. Most languages have some pros and cons. They can range from, learning curve, performance, adoption rate, community support, stability, professional support, etc...
I have hit my wall a few times in my career, C# to Java, jQuery to ExtJS, but now I have learned that I know about all of them and I know about learning them. I have forgotten almost everything about MooTools and even ExtJS (its been almost 6 years since I used it), but I know I can learn them again if needed. I also have learned how I learn. Learning new languages has gotten SO much easier with things like repl.it, jsfiddle, jsbin, codepen.io, etc... You can play in sandboxes. With .Net core being open source, you can write C# applications on a Mac, you can create python scripts that make devops processes dance, you can learn powershell basics in a weekend, you can create a hello world in haskel, you can create a neural network using google apis in node.js, the list goes on.
You WILL hit a wall. The question is when you hit that wall, what are you going to do? Are you going to stop learning and fight for the framework you spent your past 2 years learning? or are you going to investigate the new framework/language and realize it is better than your comfort zone. Your comfort zone is exactly that, comfortable. It is not challenging. It is not pushing you. It is allowing you to take pride in what you have done, not what you can potentially do.
You are not alone in your journey as a developer, you have much more of a community than I did when I started on my commodore vic-20 (yes, I eventually got a c64) but I even sought out others then to learn. Now, you can get online and say, "help me learn..." and the tutorials will come to you... go to meetups. go to forums, ask questions, admit you don't know something and need help. It will save you hours of time and you may meet someone who becomes your partner in learning.
I hope this helps a little for those struggling in the latest framework/language/api/library. Go create something amazing, the world needs your ideas.