But since "some people" asked: No caster in our party has burning hands itself. However, the bard has thunderwave, which he most recently used on a big swarm of crawling claws and before that on a giant crayfish thing. And the wizard has magic missile, which he casts at... well, pretty much everything.
Magic Missile has all sorts of useful properties, which renders it incomparable against other spells. It's not strictly
worse than any higher-level spell, since no higher-level spell can do what it does.
And even Thunderwave has a useful push component. One of the earlier arguments in this thread is that non-damage spells maintain their utility without regard to level.
Why do you assume that a 9th-level spell slot is a constant unit of magical energy? D&D magic doesn't run on energy that way; if it did, we'd be using mana or spell points, not slots.
It certainly seems like the most consistent explanation. Higher-level spells require higher-level spell slots because they require more power, and the capacity of a spellcaster to channel enough power all at once is limited by the experience of the individual, as is their total capacity for magical energy.
If that
was how the game world actually worked, then I
would expect to see the game rules as they are in the book, because those rules actually
do reflect that reality fairly well... aside from the scaling issue which is currently under contention. And while it would make
more sense to be using mana or spell points instead of slots, it's easy enough to see how they ended up as they did.
And how on earth is burning hands supposed to be "confining" its energy? It's not confining anything; it's spraying it everywhere! Surely if you call up a fire as hot as you say, it's going to spray farther than 15 feet.
Fire isn't a physical
thing in real life; it's a process which matter can undergo, in certain conditions. Given that free-floating fire is an entirely magical concept, there's no way to say how it
should work, or how far it
should spray.
If you like, you can think of it in terms of performance optimization: a meteor swarm spell is optimized for a 9th-level slot, so it's getting the most out of it, whereas a burning hands spell is optimized for a 1st-level slot, so there's a massive amount of waste at higher levels.
This is a somewhat more-convincing argument, although it assumes a lot about the setting, that there are powerful experimental-arcanists who conduct magical research on how to get the most performance out of their spells.
It also goes back to the underlying intent of the rules, though. Given that the designers
could say that magic works however they want it to, then
why would they decide to penalize multi-class spellcasters by making their high-level spell slots so weak? It really seems like a trap, that they would tell you that a split-level wizard/cleric has full spell slots,
and that you can up-rank your low-level spells to
use those slots, but then design the scaling rules so that you're strictly
worse in terms of what you can do with those spells.
And of course, the fact that the bard gets all of those spell slots
and access to higher level spells, while poaching the best spells from every other class and only requiring one high ability score, really goes to show the vast disparity in power level between characters that are conceptually similar. This edition was
supposed to be a step
back from requiring such system mastery!