You should read this interview [1] and watch the talk [2] by node's creator Ryan Dahl to get a better understanding of where it comes from. There was much more to it than "we really like javascript" (tldr: single-threaded, evented, dynamic, freedom to write new I/O apis, backed by huge companies, well known).
[1] http://bostinno.streetwise.co/2011/01/31/node-js-interview-4...