Maybe not true for everyone, but I find when working on quick prototypes of web ideas, where I have to write both front and back-end code, the fact that they're both in the same language with node.js is actually a huge advantage -- much greater than I expected.
IMHO the main problem is that usually front end development implies XHTML/CSS integration and/or UI and/or UX, and that's a very different job from back end development.
