I couldn't disagree more with what I assume you are implying here - that node is just some trendy thing that people are only using to stay hip. I have a fresh perspective since I have only been programming (mostly web dev) for a few years and I've been learning on my own with the goal of full-stack competence. I did not care about what was hip, I cared about what would work using my limited resources. With that goal in mind I have spent my time practicing, testing and analysing most of the popular languages and related frameworks from asp.net, php, python, ruby and so on, and from my beginners perspective (which is a important market to serve) node is on another level. I'm fairly confident it is one of those big leaps forward like rails was and will be around a very long time.
Why? In one word I'd say its speed. Its freaking fast and I'm not just talking about io performance, thats just the icing on the cake. Learning curve, development time, configuration, all extremely quick and easy.
One thing I think people forget or don't put enough emphasis on is that node is a networking library, its not just server side JS the way that asp.net is server side C#, its JavaScript from the bottom to the top. Web server, load balancing, pretty much anything you need can be written in just JS. That makes it extremely easy to set up your own stack that you actually have the potential to comprehend or even write yourself and launch something on the cheap. For 5 bucks on digital ocean you can set up a node app that will probably scale enough to survive a slashdot effect or launch a mvp.
Node and its related frameworks still have a ways to go but I think it is a mistake to dismiss it. And finally I'd like to mention that its first release was 2009 and people have been talking about it a lot ever since. I think its already passed the trendy technology phase and will continue to see widespread adoption.