You don't need to install custom ROM's or anything, good reason to root, and still run stock, is for AdAway app, to prevent ad's, that can drain battery, and DroidWall a firewall program, and install some basic themes that require root.
A Nexus phone is designed to be rooted in my opinion, I mean, it is the "developer phone" after all
I am no tech God by any stretch of the means, just know basic easy stuff. Rooting at first was scary and difficult to me, but this guys website was a godsend, he has a site for every Android phone, and explains in easy to understand steps, 1...2...3...etc. how to root your phone. Even includes pictures and a video of the exact steps to go through. Without this site I wouldn't even try to root my Note 2, but with his page and video, it literally took me all of five minutes, if that, and worked on the first try.
Nexus 4 root;
http://nexus4root.com/nexus-4-root/how-to-root-nexus-4-windowsmac-osxlinuxubuntu/
I am not a programmer at all, I know nothing about code. But I just followed his steps, one by one, exactly what he typed, and it works, and he makes it so easy for us noobs to understand.