> But still, having dealt with library version issues sometimes, I think "concurrent library versioning" and "sophisticated package management" sound awfully nightmarishly black-magic to me. I guess I would be more on the "let's understand the most of what happens and not change what don't need to" kind.

Concurrent versioning lets you do the "not change what don't need to" part really, really, well. Versions of packages that have been proven to work well with one another can continue to do so because if you need a newer version of some library then both the old and the new version can live harmoniously in the same codebase. You don't need to be paranoid about upgrading modules anymore because node and npm are already paranoid on your behalf.