[Sarinpa1]

Seeing traps made me think, why couldn't we build campfires?

It'd serve as a portable kitchen, but probably have very limited roster/increased difficulty to reflect that its just a campfire, not a kitchen stove or something along those lines. You don't have to haul ten food items, just cook in dungeons.
Perhaps even serving as some sort of a rest point, giving you the option to rest, which'd recover to a maximum of ~30% HP/FP (Just a random number that I thought would be reasonable.)
But most of all, the ability to use any small area and setup a nice roleplaying spot. Adventurers are very happy to sleep at an inn, but if the times aren't good, a nice spot by the fire in a forest is all they need. They can share meals, tales or whatever the hell do adventurers do.

[Prism]

I agree with this 100%. I agree with pretty much anything that adds a bit of atmosphere to the game. Tree chopping and farming is already pretty darn cool, so this would be a more general-use thing to see. It'd make the arena a bit nicer than just people standing around on grass, too.

I would want it to last a good bit of time, though. Maybe like, a few ingame hours, and extended duration if you add some ashwood/firebark to it after it's made. Nothing too unreasonable for resource costs though.

[Kameron8]

Sounds fantastic, so long as people can extinguish campfires at will. No need to have an entire city of campfires that nobody can put out for a few hours.