James Gasik
We don't talk about Pun-Pun
I'd be lying if I didn't say that playing a Wizard in 2023 is a far more satisfying experience for me now than it was in, say, 1989. However, I don't think the issue is really that Wizards became less punishing to play.Older editions of D&D have arguably more balanced casters. At least back in the day the MU was fragile as glass and had to be very careful/judicious about when to even cast their spells.
Setting aside the root problem (specific spells being overpowered) the caster's kind of just get it all and don't have to sacrifice anything.
I mean, let's look at what has really changed for Wizards.
They gain 1 more hit point per level on average, and 2 more hit points at level 1 (since max hit points are now standard, no 1 hp Wizards).
They level up at the same pace as everyone else- kind of a wash, since Fighters also had hefty xp requirements, and Rogue levels are no longer strictly worse than levels in other classes. I suppose Clerics got hurt the worst by this, but they got more toys, so whatever.
They have the same chance to hit as everyone else. This makes spells that require attack rolls worth looking at, and we don't have to have a subsystem for "magic Thac0" or "touch AC". Also, if a character has a very low chance at success at attempting a task, one wonders why we would want them to be attempting that task as part of their normal play loop.
They have less spell slots now compared to earlier editions, and since most spells require concentration, cannot layer spells of any kind, be they party buffs or enemy debuffs. The only thing they can keep casting (for the most part) is HP damage spells. I see this as a wash. Sure, no Sleet Storm + Stinking Cloud combos (good), but no making the entire party Fly when an encounter calls for it (bad). Especially with what I see are needed buffs for martials ("Sorry Mr. Fighter, no Haste for you, I need to keep this Hypnotic Pattern going, and you can't keep enemies off me anyways").
Spells are in general far weaker now than they were 20 years ago.
Spells are less likely to be disrupted now than they were 30 years ago- a wash, since apparently we don't want a Defender role or any particular way to keep people from attacking our pointy hats other than hiding in a corner somewhere.
So why is this a problem?
Because non-casters didn't really get the same buffs.
Rogues fare the best here, as Sneak Attack is a reliable source of "do things in battle"; 3.x Sneak Attack had too many caveats, and Backstab was nigh-unusable.
Barbarians are almost totally reliant on what is, in effect, a "spell slot" ability that lets them be awesome for a few fights a day (but even then, it has a lot of caveats).
Fighters? What do Fighters have now that they didn't have before? They lost Weapon Specialization, they lost a suite of special combat feats built for them to use. They gained a minor self-heal 1/combat, Action Surge to make up for losing Haste, and a couple of free rerolls of likely poor saving throws. Contrast to the Fighter of 30 years ago, who had the best saving throws at high levels of anyone! Where once they got 11 bonus Feats (assuming their table uses Feats), they now get 2. Sure, maybe Feats do more now, but is a 5e Feat 5 times as good as a 3.x Feat? Sadly no, and 3.x had some whoppers like Combat Expertise!
They lost magic items. Even if you argue that, no they didn't, since the DM can still use this optional content, most of the items that boost the weaknesses and utility of the Fighter class require attunement, limiting you to using three at a time, ever! I can't stress how badly this nerfs everyone, but especially the Fighter, who now has to rely on others for things like immunity to death, freedom of movement, flight, the ability to survive on other planes...with no guarantee that their party will have a caster who can provide such, has the spell slots to do so, or can spare the concentration!
Now before anyone says "but wait, they got Subclasses"- not only did we have those 20 years ago in the form of Prestige Classes, everyone has a Subclass. And magical Subclasses are often strictly better than non-magical ones, and not even then- Eldritch Knights get to be 1/3 of a Wizard and Bladesingers get to be 1/2 of a Fighter.
Ultimately it's not that what Wizards and other spellcasters got that was too much- it's that other classes didn't get enough, and not enough thought was given to how classes support each other- casters lost ability to effectively support martials, and martials got very little to make up for that.
The argument of course for doing so was that casters were using these toys to support themselves back in 3.x, and I agree, they were. But reducing spell slots and making a caster only able to concentrate on one spell at a time only fixes half the problem. A simple fix of "the recipient of a buff spell must maintain concentration on it" would have at least addressed the issue, if not solved it completely.