Yes, I think is better to put nginx in front to handle this and sooner or later you will need some kind of reverse proxy as soon as your application grows. The reasons might be load balancing or just to map components of your app like "app.com" and "app.com/api" being different applications.

One big difference to note is that nginx link to the local openssl while node binaries embeds an openssl. If there is a bug in openssl I can apt-get update/upgrade and I get the patch very early.

Personally I think nginx is awesome. They are going to support JavaScript soon, but I have done things with LUA and is great too.