I used to be one of the people who didn't name any of their team members, but around the time I got Emerald I started nicknaming, and now I've gone back to some of my past games and starting nicknaming there as well.
One of my favorites is from my original Emerald file, it was a used game and the player started with Torchic, it was named "Firfbreath" (Firebreath spelled wrong?) and I renamed it Colonel. It sounds cool and it's a KFC reference. Colonel now resides in my Diamond file along with the rest of the team from that run.