The abillity to not having to draw a hand drawn map, having to remember a huge cave system not have to refer to an external site for such a map is surely more than worth the efforth. Doing a map is simple, it shouldn't take more than a day's work, probably not even that much.
If so many people have asked this already, surely it's not a wasted feature, but hey if some people don't like it, they just have to not click the map key.