Why Node.js devs tend to lean towards the Module Requiring vs Dependency Injection?

Dependency injection is somewhat the opposite of normal module design. In normal module design, a module uses require() to load in all the other modules that it needs with the goal of making it simple for the caller to use your module. The caller can just require() in your module and your module will load all the other things it needs.

With dependency injection, rather than the module loading the things it needs, the caller is required to pass in things (usually objects) that the module needs. This can make certain types of testing easier and it can make mocking certain things for testing purposes easier.

Modules and dependency injection are orthogonal: if you need dependency injection for testability or extensibility then use it. If not, importing modules is fine. The great thing about JS is that you can modify just about anything to achieve what you want. This comes in handy when it comes to testing.