It’s that they are more wasteful, less reliable, more time consuming and don’t mesh with the core benefits of the game as well as the things that martial’s do
Then in this, you are simply, flatly wrong. Well, not wrong about the greater
potential for waste, I certainly agree with that, simply because a wasted attack roll is almost a trivial non-cost. But you are wrong that they are that much less reliable, particularly for a player who puts even basic thought into spell selection*--they are by design approximately equally reliable, and
more reliable if you know your enemies and can pick their weak saves. Because Fighters don't get to pick a monster's weak defense. There's only one. AC. They're either lucky and fighting something with low AC, or they aren't, and fighting things with middling to high AC. Even the mere
possibility that you can try targeting different saves, when essentially every monster has at least a couple weak saves, already puts casters in a superior position. They can actively seek out weak points. Fighters can't.
*E.g., have spells that target different saves, preferably ones that are often weak like Int or Wis; have different elements that are rarely double resisted, like fire
and lightning, or cold
and acid, or just flexible spells like
chromatic orb; have buff spells that are essentially never not useful, e.g.
enhance ability,
haste,
fly, etc. It's
really not that hard to pick 2-3 spells per spell level that are generically good...which still leaves room for more spells later.
I would need to know what you think "the core benefits of the game" to respond to that portion.
Also, plenty of strong spells have attack rolls.
Scorching ray is a great spell, and it uses spell attacks. 5.5e Wizards alone have 16 spells that either are just a spell attack, or enable you to make a spell attack (e.g.
witch bolt allows you to repeat the attack against the target). Further...you don't benefit from Advantage...you instead benefit from your opponent suffering from disadvantage. Which isn't as hard to apply as you might think. Crits are the one thing that rolling attacks has but forcing enemies to roll saves doesn't.
Or the fact that there are a plethora of powers and abilities that prevent spells working efficiently.
Would you care to name them? Because I'm not familiar with that many. It would in fact please me
greatly to know that the game actually provided teeth to a DM who wanted to place limits on spellcasting. I am entirely sincere on this--if you can in fact prove to me that there are a "plethora" of such things, I would be only too happy to agree!