I never saw Far Cry's editing tool, but your idea is great. Map making for FPS games is usually the realm of a very very small elite, probably less than 0.1% of the total player base. Meanwhile, we know that gamers really love the ability to modify a game.. just look at The Sims and Neverwinter Nights. Both those games are of course producing more generic-looking content, but there's gotta be a middle ground where the generic toolsets and the super specific stuff of Hammer can meet. Or, at the very least, Average Joe map makers should be able to easily create new quests/missions/enemy locations/scripst on maps that are created by the Elite Joe Map Maker. So you'd still have just a handful of map makers, but you'd have a legion of people who could reinvision each map.
You know what I really want in a MOD? The ability to be a "dungeon master", like in Neverwinter Nights. So the players have an empty map, but the DM plops down enemies in real time, and can, on-the-fly, create new dialogue, missions, and so forth. Now that's a co-op experience!
Adventures of a video game mercenary
http://virtualmerc.blogspot.com