This is why I don't envy your table.

The idea that someone would want to play a dragon sorcerer and convert all their slots into sorcery points just so they could cast Twinned Firebolt over and over and over and over and over and over... and that's FUN for them? Yeesh! No wonder you get bored watching your players do the same things with the same build repeatedly. If just cranking out hit point damage is all that matters to the group... it explains why you want to try and find different ways to create such damage, just so they vary up how they accomplish it.
The problem is, you don't sign a contract never to cast Fireball or Forcecage when you create this character. The flexibility is enormous, once you shed the expectation you're supposed to use most or even many slots for spells.
About the fun part. Killing monsters is fun. Killing the most monsters the fastest is more fun.
Whacking/shooting monsters with a longsword/longbow all day is no more fun than blasting them with cantrips. In fact, if you deal nearly half damage, it is way less fun. (Having to bother with magical resistance is even less fun. Constrast the "sorcher" who simply switches to cold damage or something as soon as she sees the Fire Magmins or whatever)
The point here is: you can have two sorcerers, one acting as the spellcaster, the other acting as the archer. You can even switch roles each day, or have no archer one day, and two archers the next.
I don't see how this is inherently any less fun. Your class is after all only a tool. I can describe my character as an "arcane archer" despite not touching the Fighter class. If building this "martial" character using the Sorcerer class yields almost twice as good results, why not?
The designers are doing a bad job when the balance can be broken in these ways. But more importantly, I wish to do their job for them so the game can be actually balanced, and thus, more (not less) fun
After all - the real gain is all the previously not-good-enough builds and feats and whatnot. My main aim is to allow players to pick all sorts of builds, weapons, and class features, without feeling they have to sacrifice significant utility (which in a combat-heavy game is equal to "dealing damage").