Indeed, I am concerned about the trend towards locally installed NPM modules, away from globally installed ones. The other project exhibiting this trend is ESLint. It used to work beautifully globally installed, then the developers broke it; it's better now, but there are still some bugs. Having one ESLint config per project and making it a direct dependency is ridiculous when you have a dozen projects and all you want is in-editor linting (in Atom, in my case).
The problem is that you can't require global modules, so that global module needs to have installed everything that needs, and if it needs to support multiple projects with different requirements, that global modules needs a whole lot of modules itself in its package.json, and now that global module is unmaintainable, because of all its dependencies. That is why global modules is generally not useful and that it is better to have them installed locally.
