Not to mention that this crappy feature forbids ents from making rangers. Oh,
and ent druids can't make fires

Why not go along with Ramjett's idea, that
they would at least stomp out those fires after a few seconds in the room, not
right at entry? And maybe make someone with _mastery_ of fire building make
safe fires, i.e. 'unstompable'? After all, master of fire building could
affect flammability of the surroundings in a positive way?