The Node.js ecosystem has a lot of potential, but the variety of off-the-shelf add-ons is severely limited compared to either of those more mature frameworks.
If you think Node.js is easy, you've never really experimented enough to understand what makes Rails so effortless. It's a lot easier to produce a production-ready application with Rails than it is with Node.js as it is today.
In four years, as Rails starts to add less critical features, Node.js may well have caught up.