I've found that a large subset of programmers share the same trait as a large subset of photographers: they become so obsessed with tools that they lose sight of the fact that the end product is what matters at the end of the day. For example: there are many people who spend thousands on cameras and gear, and still take terrible photos. There are many developers who spend a lot of time keeping up with what they think…
The second sentence really tells all. " Just learned Backbone.js and only found out it’s already out of fashion ." This is why critical thinking and a sight of the big picture is so important. Who cares if something is fashionable? Does Backbone help you solve your problems? Yes? then use it. No? Don't use it.
This really bears repeating over and over again, and I think it's a corollary of "start by writing the dumbest thing that can possibly work."
If you start with dumb, simple things, the problems become more obvious. Dumb simple things tend to shake out the parts that are tedious to build, or non-conformant, or confusing to read, or hard to maintain. It may be that Backbone (or any of the dozens of other gizmos) alleviate the problems, but you really have to understand the problem first.
I really think a lot of people are seduced by the marketing of various tools and frameworks into thinking they have (or will have) problems that they don't actually have. Then they end up with over-engineered solutions that are all the things they hoped to avoid.
Don't meant to criticize backbone, or any other framework (or language, or platform). A fancy, hip tool can be just thing. The question is: do you know what "the thing" is really for, and does it fit your situation?