I worked on a mod for Battlefield 2 several years ago, AIX 2.0 mod. It was alot of fun and the group behind the mod was amazing.
I made AI navmeshes for the maps that the map makers would develop. It was tedious but rewarding when you saw you map being played and the AI navigating the map with your navmeshes.
Nevertheless, I hope AI tech can make that a thing of the past and bots can come to a point where they can not only navigate but "act" like humans and take positions, snipe, flank, etc etc.