Those features are a lot of the reason for it, yes. As a cool example of what can be done with generators, check out my colleague Dave Herman's task.js library: https://github.com/dherman/taskjs

That library gives you coroutine-style I/O on top of node.js primitives, which is, as far as I can tell, the #1 feature people have been asking for all along in Node. It only works if node.js implements coroutines (which Ryan has so far refused to do) or if the language implements generators (which you get with SpiderMonkey).