Daztur
Hero
The difference is that Crack the Shell doesn't have any relevant keyword. Fireball does - it has the [Fire] keyword and deals [Fire] damage.
Unhappily, the only clear discussion of the relationship between keywords and fictional positioning in the 4e rulebooks is in the DMG, in its rules for attacking objects.
Nevertheless, the keywords are obvious anchors between the effects and the fiction. Something has the [Fear] keyword and inflicts a push - that means it makes you run away! Something inflicts [Fire] damage - that means it is not kind to paper! Something inflicts [Cold] damage - that means you can use it to freeze a stream to avoid having to wade it. Etc.
This is ignoring keywords.
You can't "refluff" a fireball as being a ball of stinging bees that disable the victims - that would be a [Poison] effect, not a [Fire] one.
This is also why martial abilities are more easily "refluffed" than magical ones - which is a particular instance of the more general phenomenon in 4e, that magical abilties are generally most easily read as (perhaps rough and ready) process simulations, whereas martial abilities are often most easily read as metagame player resources rather than fictional PC resources.
Interesting discussion on how martial and arcane stuff differs in 4ed.
From what I've seen the keywords will be there and more important in 5ed.
But you can refluff fireball to some extent in 4ed. You can summon fire out of the ground, send a swarm of fire-breathing bees at the enemy, have fire erupt within the heart of each enemy within the area of effect, whatever. This wouldn't fly in 1ed which has the fire expand outside of the range if it is caught in, say, a tunnel (leading to you having to do volume calculations, ugh) or in 3.5ed which has that bit about the magic bead that you shoot.
OD&D doesn't use keywords, true. But given how scant its prose is, you probably won't go too far wrong if you hook onto the obviously referring terms and treat them as keywords.
Fair enough. In that case then I don't like flavor text that can't be treated as keywords.
If I was playing B/X, and the GM ruled that I took ongoing damage from a fireball, I would regard that as tantamount to cheating. A sword of wounding, which causes (from memory) 1 hp/round of ongoing damage, is one of the most powerful items in classic D&D.
For me at least DMs being able to rule on how the keyworks work in any situation is important for rewarding situational cleverness. I wouldn't apply that damage all the time but if a character was wearing thick flammable clothing and then got hit by a fire spell I sure would...