Imaro
Legend
Those "rules" seem to have about as much weight as the flavour text for Spinning Sweep.
No, I would argue the rules for the fireball spell + the rules for damaging objects have alot more weight than "the flavour text for Spinning Sweep"...
Do those rules tell me how much damage an object takes while burning?
1d6 per caster level. Once it has taken this damage it is no longer burning.
How about how fast the fire spreads?
Who said the fire was strong enough or lasted long enough to spread? The magic creates the fire and the magic's duration is instantaneous. The fire lasting longer than an instantaneous burst is not part of the description for the spell... so it lasts as long as it takes for the objects to suffer 1d6 per caster level of fire damage.
What's needed to put out the fire? How long something will burn?
The fire in this spell only lasts long enough to do 1d6 per caster level of damage (again th duration of the spell and thus the magic fire it creates is instantaneous). The rules for damaging objects allow one to determine what did and did not survive the burst of fire damage that the flames of this spell were able to produce.
What I see, if those rules are applied, is that combustibles will catch fire and, if not destroyed by the initial damage, burn forever like the cast-aside ironwood staff.
This is because instead of actually following the rules in the spell and for damaging objects (which will let you determine what objects were destroyed in the fire, and what objects were only singed or suffered minimal damage)... you've ignored some things and added your own interpretation/rules to it... then wonder why it doesn't make sense.
Nowhere does it say the fire lasts forever or that once ignited the combustibles stay lit. Just follow the rules for the spell and damaging objects (which even has specific rules for fire) and it works out.
See LS, I think you're missing the bigger picture. The fact of the mattter is that whether you like or don't like the way fireball in 3.5 interacts with objects... it's accounted for, made apparent to the player when he chooses fireball, and consistent in the rules. The interaction of a fireball with objects in 4e, on the other hand, isn't consistent, isn't accounted for in the rules, and even whether it's up to the DM or up to the player's requesting it from the DM is in the air between people who play the game.