There are a couple of things that concern me about it and the most pressing is security. It is just so easy to include hundreds of packages the source of which is almost impossible to track.
If those modules are maintained by people you don’t know anything about how do you know they can be trusted. How do you know if someone has not changed the code somewhere in those packages to do something malicious.
But that concern was precipitated by my very first concern. The sheer number of packages you can install without even trying to do so. Next time you play with node just check how many packages youhave just by including express and a couple of components.
And then finally perhaps the reason that appears to be the most churlish is that just because anyone can now write backend code with JS does not mean that you should. Sometimes Node just does not do the trick. If you want to create a system that processes and transforms lots of data, Node is not the right tool.