Do you really think people would give up spellcasting if there were a few more restrictions on its use?
It depends on what those restrictions are, and how annoying they are to deal with. For example, when I was playing AD&D, people rarely played Wizards in my experience. Curious as to why (since it sounded like a cool class), I played one. Soon I found that as if limited spell slots, almost no survivability, slow xp progression, and being the bottom tier of usefulness when I couldn't use magic wasn't enough, I had the additional issues of:
*Dependent on RNG or DM mercy for new spells.
*Scribing spells into my spellbook were expensive.
*Some spells requiring difficult to acquire and/or expensive components.
*Instantly losing a spell if I took the slightest amount of damage (on top of losing my Dexterity bonus to AC).
*Most spells being "save (neg.)" and saving throws becoming more likely as I leveled instead of less.
*The occasional case of a spell not working as advertised on an opponent.
*Magic resistance being handed out like candy to various monsters.
Despite playing for decades, my highest level AD&D Wizard is 9th, while my highest level non-Wizard has reached such a ridiculous level of power that we don't even track xp or use a character sheet anymore- there's not much point. They haven't ascended to godhood or anything, but they regularly deal with such powerful entities.
AD&D players will tell you that this is working as intended, because Wizards eventually gain mighty spells (amusingly ignoring the fact that none of the above issues ever go away, at best you can mitigate them- and most of the ways to do that require magic items or specific spells that you again, have little control over acquiring).
However, the game really kind of wants someone to be playing a Wizard- there are challenges that require their spells as the game progresses. But if the only people who play Wizards are those who enjoy playing on hard mode, and no one in your group is feeling like that kind of challenge, you have no Wizards.
Which puts the onus on the DM to either adjust the challenges so the party doesn't need a Wizard, or chuckle at the foolishness of the players for not doing so when the adventure calls for Wizard magic.
I mean heck, TSR noticed that people weren't wanting to play Clerics, despite them having several advantages over the Wizard (more hit points, way better armor, bonus spells for high Wisdom, hypothetical access to almost every Cleric spell ever created on any given day) and seriously ramped up the power of mythos priests, until they were literally the most powerful classes in the game by the late 90's, presumably all in an effort to lure people into playing the healer!
WotC came to the conclusion that the ideal party was Fighter, Wizard, Cleric, and
Thief Rogue, and made adjustments to the classes in an effort to make sure someone would actually want to play these classes (to varying degrees of success); something they still struggle with to this day!
And really, when it comes to Wizards, what has really changed?
*Scribing spells into my spellbook are expensive.
*Some spells requiring difficult to acquire and/or expensive components.
*The occasional case of a spell not working as advertised on an opponent.
*Magic resistance being handed out like candy to various monsters.
Are all still true, so it's only:
*Somewhat less Dependent on RNG or DM mercy for new spells.
*Have a chance to lose some spells when I take damage.
*Most spells being "save (neg.)" and saving throws becoming somewhat less likely to succeed as I gain levels.
A lot of people talk about the fact that Wizards are less encumbered than their past incarnations, but no one bats an eye at a class in a similar position, the Rogue.
The modern-day Rogue almost has nothing in common with the AD&D Thief; the almost impossible to employ Backstab morphed into a slightly easier to employ Sneak Attack, which continued to become easier until today it only has token restrictions at best- heck, they can use the ability at range more easily than in melee! Incredibly low chances to perform thieving abilities with scores of caveats has become game-warping bonuses to skills.
Imagine if you replaced the Rogue in 2024 with the 1e Thief class- how many people would play it, do you think?
