It seems realistic to be able to burn things down, however having it as a reward for learning fire building skills seems oddly supportive of pyromaniacs. But, I guess that would be good to have as part of your arsenal when you go to war. I think that if this is implemented it should have consequences similar to killing someone: even if no one finds out that it was you who set the fire, you would know, and your guilt would be reflected in your stat loss.
Other issues to address would be how nearby structures and items would be affected by the fire. Would they also catch fire, or would you have to set each fire separately? And, would there be smoke damage to the items inside, or to buildings adjacent to the burnt structure? If the fire is set while tribe members are present, would they be able to fight the fire in an attempt to save the nearby structures? Would the fires last longer when the materials of the structure are more dense? (Would a tent burn faster than a log wall or fence?) Would a stone wall, post, or metal wall be affected at all? Would the fire turn the ground tile into ash and charcoal, and if it does, would they become usable resources?
There would be a lot of questions to figure out to implement arson as a skill. And, ultimately, I think it would be abused as bad or worse than the current logging situation: It only takes one person one action to chop down a tree no matter how big it is. Our world would be a desolate barren wasteland, and no one would want to play longer than their trial period.
Arson? Oh lord, why cant people focus on creation instead of destruction?
I would like to see more types of fire instead. Right now we have only camp fires. How about bonfires (larger then campfires), torches (can be carried in a hand or placed on enterances of camps or placed on walls. Then furnace builiding for metal crafting profession? Possibilites are limitless if you stop thinking about destruction for one second.