Global packages are harder to maintain. Let's say you installed foobar version 5 globally last year. This year, you're using a newer version of the foobar packa

Global packages are harder to maintain. Let's say you installed foobar version 5 globally last year. This year, you're using a newer version of the foobar package that isn't backwards compatible. You install it globally, which replaces the old version 5. Now if you go back to the old project, your use of foobar is broken. Depending on the package, it might be fairly invasive/difficult to simply update. For myself, I always install global-recommended packages as dev dependencies. It can be a little painful, but it also means there are no special install instructions, and it _just works_ (tm).