I would just add to the idea a MapMaking skill and a MapReading skill to the game. That way, even if you did get hold of a good map, you'd need to know how to really read it to get the full benefit.
Likewise, not many people can actually make an accurate map. In order to make a really good map, you'd need high skill. Similarly for copying, not many people can accurately copy a detailed graphic document, without having skill to do it.
A cool enhancement would be to add a screenshot journal, so that as you tag a location on your map, you could embed a screenshot too.
I like this idea, only one thing I would see changed on it. I dont think it should auto add tribal boundries. I think if you want to add a 'tack' to the map and show a tribe there then thats fine, but I wouldnt' go with the autodraw of tribes. If you really want the tribes added to your map I would say it should be an at the totem option. Right click a tribes totem and select 'add to map'. There should be a personal interaction required to add a tribe to your map, not just walking past it. Doing this would significantly reduce the database draw on the map system.
actually, a MMO called ArcheAge have already implemented this, they will have a Adventurer Class that is specialized on writing and discovering new maps, and selling Compass,
but yeah, having this feature will definitely help alot!