That's an easy question. It makes it so you can install MS Build tools!
And that's about all I know about it. Wish I had a better answer for you.
When you installed node.js, did you use v4 or v6? PTD says you can use either, but when I tried to use last known stable, v4, I had problems. You'll want to install v6. It cured some of my problems, but don't know exactly which. I did my CLI install the afternoon it was released.