The reason it needs to be changed is because it pushes out all other spells. We played a campaign from 1 to 15. At 15, 60% of all spells being cast were still fireball.
I like that fireball remains a staple spell throughout a wizard's career. It sure beats 4E where spells go obsolete in five levels or so.
I've got a bard too. No fireball. My group doesn't care. Just because the other players think fireball is the only good choice and are being jerks about it doesn't make it true. Cast revivify on one and ask if they'd still rather you had blown their sorry corpse up with fireball instead.
But ALL spells should remain a staple, not just one. I should have a reason to cast Magic Missile, Burning Hands, Ice Storm, or Shatter when I'm level 10. Especially if I'm using a 5th level slot to cast them. But I don't have any reason to do that because I could be casting a fireball instead, which is better 80% of the time.
We used them both during that campaign. But you'd be surprised how easy it is to fit it most of the time. It's a 20 foot radius, but nothing says what happens to the portion that gets cut off by walls. Back in 2e, when it would expand to fill the same volume, it was dangerous and I'd avoid casting it if at all possible. But now, we open the door to a 20 by 20 foot room filled with monsters, we go first, we put the focus point of the fireball at the back of the room, affecting everyone in the room and none of us. If that doesn't work, we throw the second or third fireball. Most battles ended without attack rolls being rolled by the enemy. Our Wizard also had the class feature that let him exclude squares when he cast it, so he could often skip the 2 or 3 of us that were in the fireball radius when he cast it.
No one ever died during that campaign. Revivify would have taken up a slot for no benefit.
Then you need more variety in your antagonists, or a change in thinking. Because I continue to use Magic Missile, Ice Storm, Lightning Bolt and Ice Storm on fairly regular basis up til around level 11 or so, when my games die out. Not so much Burning Hands, but that's always been a quickly dropped spell for me, no matter the edition. I have kept it may times, however, just in case of the event of rodent or insect swarms. And I don't think I've ever actually played an Evoker either.
As you go on to note, the word "always" is hyperbolic. But more important is the word "if". Yes, fireball is very good at what it does: damage. If your character is a blaster mage this spell should be in his or her arsenal. And I don't see the problem with that. It's the spell for throwing a ball of fire at the enemy, which is what most blaster mages in most media spend most of their time doing. (And what they're doing the rest of the time, throwing bolts of lightning, also deals 8d6 damage.) But not all mages are blaster mages. Sometimes mages want to do things other than raw damage.
Ice storm is a hybrid spell with a decent crowd-control effect on top of its damage. It doesn't need to "curve" off of fireball; they serve different purposes. (And together, they don't make for a half bad one-two punch.)
You can call them that if you like.
No. You can't make something good or bad by defining the term for it that way. You have to actually demonstrate why it's good or bad. Look at what @Majoru Oakheart is saying. I'm disagreeing with him at points, but he is giving concrete reasons for why he thinks fireball is bad for the game, and that's the correct approach.
Did you know the original pitch for Magic: The Gathering was "the game where every card breaks the rules"? (I may be paraphrasing a bit.) Is M:tG a badly written game? Over the past couple of decades, game designers have grown increasingly aware that judicious rule-breaking is not just tolerable, but actively beneficial for many games.
What if I said that revivify was way ahead of the curve for the cleric, because wizard conjurers can't do anything like it at 3rd level (or any level)?
You have yet to establish that fireball is a "mistake".
"There's no reason for X" does not imply "X is bad". All you're doing here is subtly shifting the burden of proof. When you're the one complaining about fireball, it's your onus to discredit it, not my onus to justify it. Again, look at what Majoru is saying: "8d6 fireball is bad because it hurts my gameplay in these specific ways."
Then why are we comparing the psion to the wizard? When the wizard gets no healing spells at all, that's simply the extreme of this differing-power-budgets thing I'm talking about. If we added some wizard healing spells, but they were let's say half as powerful as cleric healing, would this make the wizard suddenly underpowered? Of course not.
On the same class list? That's not what we're talking about.
I actually just happened to run into one preparing for a session today: divination is a level lower but considerably better than contact other plane. It's not a complete apples-to-apples comparison, but if I were a bard looking to choose a question-answering spell I know which one I'd pick.
But I'm not comparing with non damaging spells for a reason. If you are a blaster mage, then you want blaster spells. And you want more than one of them. Fireball makes that impossible by making all choices but one completely suboptimal. No one takes lightning bolt because it has to start from you and shoot forward. It only affects people in a line and, most of the time, when you enter a room the enemy is not standing in one. Casters also like to stay at the back of the party and that often means lightning bolt will hit ALL of your allies if you cast it(or you have to move to the front, putting yourself in danger). It wasn't even a consideration for most people in our group because its disadvantages outweigh its damage. Which is why I didn't lower its damage when I houseruled fireball.
It creates difficult terrain...for one round....which is a VERY minor benefit. Over 80% of the time the enemy doesn't care about moving at all or still has enough movement to get where they want to go. If I'm using a 4th level slot up, then it should do as much damage as a fireball increased to 4th level. Because when I get a new spell for going up a level, it should be BETTER than the spells that came before it. And it IS better than magic missile, scorching ray, burning hands and shatter and probably better than lightning bolt(its versatility makes up for the lower damage). But it isn't better than fireball because of the inexplicable raising of its damage at the last minute.
You are using that term poorly. Magic: The Gathering works because they avoid outliers like crazy. They have a VERY detailed spreadsheet they use when creating their cards that give points for certain benefits. For the first couple of sets they didn't have the formula worked out yet. Which is why the first couple of sets contain cards that are worth hundreds(or thousands) of dollars because they are CLEARLY better than all other cards that do similar things. It was bad enough for the game that WOTC had to invent a tournament format that said "You can't play with old cards" because those people with the old cards were winning 95% of the time.
When comparing power, you must always compare like to like. Cleric spells do different things than Wizard spells. Clerics heal, bring people back to life, and cure bad effects on people. Wizards don't generally get those abilities(to preserve class uniqueness). Hussar does some good analysis above, but Revivify is a perfect reasonable spell at 3rd level compared to the levels of other spells that bring people back to life in the cleric list.
