And then add sometimes not properly defined version dependencies (or developers abusing version numbers a bit) and you have a dependency hell when running npm update -g will almost definitely break something.

I love yeoman, great scaffolding tool, but it depends on so many packages that sometimes it simply doesn't work because some package it depends on did something silly. So once you have a working set up, don't update it if you absolutely must.

That shouldn't be the case in 2014.