D&D 5E Spell Versatility is GONE. Rejoice!

[Chaosmancer]

That's mostly due to the fact that wizard subclasses don't change the base class that much, while Barbarian subclasses pretty much define who you are and what you're going to do. Bear Totem Barbarians are gonna tank, Beast Barbarians are going to destroy every enemy with a flurry of primal blows, Battlerager Barbarians don spiked armor and throw themselves into their enemies. However, most wizard subclasses play pretty much the same way (other than Bladesingers and probably Necromancers).

Here are some possible combinations of two schools of magic that can be interesting, while still fitting in with the other subclasses:

Lifedrinking Magic - Combine Evocation and Necromancy to drain the life of your enemies to heal yourself and allies. They're often used in wars to work as a healer and battlemage.
Figmentation Magic - Combine Conjuration and Illusion magic to create illusions that are partially real, and can be interacted with.
Phantom Magic - A combination of Necromancy and Illusion magic to use phantasmal force, phantasmal killer, and other illusion spells that frighten people and make them see things that aren't there.

They're not all that exciting, but they still would be valid and cool subclasses.

They are cool concepts... But the illusionist and conjurer already do stuff like Figmentation magic, and Phantom magic just seems to describe a spell selection.

I know you would add abilities to them, but Phantom magic in particular seems like it is really about buffing specific spells, instead of creating a new way to play the wizard.

 

[Shadowedeyes]

I had an idea for a wizard subclass that combined Evocation and Enchantment magic, and would reward a character who took spells from each school. I never ended up ironing out the details but maybe I'll go back and work on it.

 

[doctorbadwolf]

A Wizard with an advanced familiar, where the familiar gains proficiency in Arcana and one other Wizard class skill, and reduces the time and cost of making potions and scrolls, of enchanting items, and can reduce ritual casting time x/day.

defense benefits while the familiar in near the Wizard, and maybe the Wizard can cast more spells through the familiar.

 

[Lanefan]

Somehow you can't move a comma of the other three classes without that infringing on the wizard. Also, it is a class that struggles to come with new subclasses. Outside of setting specific variants like defiler/preserver and High sorcery there is not much themes left to explore for the wizard. And if you give sage background to either of the other three, you kind of have the same basic character types covered. On the other hand, you can't really start with a wizard and end with an analogue to the other three.

Reading the next dozen or so posts after yours, plus yours, makes me wonder yet again if there's too little territory (or too few niches) being divvied up between too many classes and sub-classes.

Were it me I'd be taking a hatchet to the lot of 'em, ending up with maybe two base classes (Vancian Wizard and Spontaneous Wizard, whatever names you want to give 'em) and then having maybe half a dozen subclasses (max, ever!) spawning off of each:

Vancian could spawn, based almost solely on their unique-to-subclass spells available:

Necromancer (these get to create and play with undead)
Illusionist (these mess with your mind via spell)
Summoner (when in doubt, add more critters)
Blastmage (a.k.a. Evoker; blow stuff up in many different ways)
Artificer (makes, identifies, and uses items, scrolls and potions far better than anyone else)
Generalist (jack-of-all-trades, just a direct continuation of the base class, best at utility spells)

Spontaneous could spawn, based on a variety of differences:

Witch-Warlock (these are female and male names for the same thing; nature- and elemental-based spontaneous casters)
Shaman (includes Wild Mage, culturally-thematic spontaneous casters and each culture's is different)
Pactmage or Bondmage (current stereotypical Sorcerers-that-get-their-powers-from-a-nasty-source)
Diviner (specialized in spell-based and innate divinations)
Psionicist (these mess with your mind via all sorts of means)
Sage (specializes in knowing stuff; would overlap a bit with Bard perhaps)

Those are all distinct enough to keep separate and to stay out of each others' way, I think.

 

[MoonSong]

Reading the next dozen or so posts after yours, plus yours, makes me wonder yet again if there's too little territory (or too few niches) being divvied up between too many classes and sub-classes.

Not really, there is little in the way of making bard, sorcerer and warlock subclasses beyond designer resources (Like I love to say, warlock subclasses are limited by the entries in the Monster Manual, sorcerers are limited by the words in a dictionary). Wizard is just that narrow to begin with. And no, it wasn't a 3.x invention, 2e wizards were like that too. With the exception of a couple of cool ideas in 2e, most wizard kits and variants were schools, and "cultural variants" that wouldn't fly in today's environment. While warlock kind of originated in the 2e wizard kits, there was just nothing sorcerer-like before we got actual sorcerers, and out of all the sorcerer variations shown so far, only one subclass clearly pays homage to a wizard kit. And we haven't finished with the tip of the iceberg when it comes to sorcerer themes. Yes, there's overlap, between sorcerer and warlock themes, but they are only superficially the same, one is making a pact with a celestial, the other is being a celestial.

Wizard just lacks that variety in themes. The designers just couldn't admit it to themselves before sorcerer existed, and for the most part, after a few years of sorcerer existing.

Edit: and really, I could make an "academy magic" sorcerer subclass, ban wizard, and we'd lose essentially no character concepts.

 

[tetrasodium]

Reading the next dozen or so posts after yours, plus yours, makes me wonder yet again if there's too little territory (or too few niches) being divvied up between too many classes and sub-classes.

Pretty much, but also there are 5e-isms that exacerbate it. Back in 3.5 the classes gained access to different spells at different levels while 5e just says that a spell is level N & you either get access to it when you can cast level N spells or you don't get the spell bestow curse, blind/deaf & many others were examples. Removing that hurt class class distinction among casters. Also you had PrCs that would give you +1 caster level(?) in your caster class so the viscerally different PrCs were available to any caster as long as they qualified, when 5e divided those PrCs wotc put almost all of them under sorcerer & warlock. Wizards also got a lot of bonus feats they no longer get & those feats themselves are largely nonexistant in 5e

As a prepared caster wizard generally had a much wider assortment of spells available than a spontaneous sorcerer (even if it was just 1 slot to a niche spell). In the3.5 days that was a massive benefit that even got more pronounced if they got really incredible with burning spell slots as a hail mary that resulted in a lot of sorcerer specific feats/PrCs getting created, many of which were directly or in spirit pulled straight into the ye sorcerer/sorcerer archetypes... but in making them spontaneous wizards lost that gold star of being prepared for anything while excessive application of concentration to spells robed them of the ability to pull that hail mary rabbit out of their hat even if they had the perfect spells.

Also removed were things like guidelines for how much purchasing access to copy spells from NPC spellbooks making the benefit of having a spellbook you could copy things into less meaningful. Doing away with the old wealth by level resulting in wizards who very likely can't afford to do much with a spellbook even if they get lucky & find a packed spellbook. While other classes move away from gold & towards adventuring as the primary way of getting awesome new equipment wizards just keep needing it in larger & larger amounts just to scribe spells they often won't have enough prep slots to make much use of. TCoE has a wizard archetype that drops the time to scribe a spell from hours to minutes but technically does nothing about cost unless you assume "the quill doesn't require ink" covers "The cost represents material components you expend as you experiment with the spell to master it, as well as the fine inks you need to record it." in a rather bizarre "erm... who is this for?" feeling.

The new spellbooks in TCoE address some of the versatility loss , but none of them are "common"/have a common version & wotc is unlikely to issue a "xyz should be added to the treasure on page x room y in oldHardvcoverAdventure" so wizards aren't likely to be walking around with a library of them & the attune requirements make sure that they can't really even if they did find a bunch

 

[doctorbadwolf]

Not really, there is little in the way of making bard, sorcerer and warlock subclasses beyond designer resources (Like I love to say, warlock subclasses are limited by the entries in the Monster Manual, sorcerers are limited by the words in a dictionary). Wizard is just that narrow to begin with. And no, it wasn't a 3.x invention, 2e wizards were like that too. With the exception of a couple of cool ideas in 2e, most wizard kits and variants were schools, and "cultural variants" that wouldn't fly in today's environment. While warlock kind of originated in the 2e wizard kits, there was just nothing sorcerer-like before we got actual sorcerers, and out of all the sorcerer variations shown so far, only one subclass clearly pays homage to a wizard kit. And we haven't finished with the tip of the iceberg when it comes to sorcerer themes. Yes, there's overlap, between sorcerer and warlock themes, but they are only superficially the same, one is making a pact with a celestial, the other is being a celestial.

Wizard just lacks that variety in themes. The designers just couldn't admit it to themselves before sorcerer existed, and for the most part, after a few years of sorcerer existing.

Edit: and really, I could make an "academy magic" sorcerer subclass, ban wizard, and we'd lose essentially no character concepts.

An academy magic sorcerer still wouldn’t be someone who learned every spell via careful study, and there’s no way a spellbook sorcerer subclass would avoid outshining other sorcerers.

And the Wizard just isn’t that narrow. We don’t have a Familiar focused Wizard, or a restoration Wizard, or elementalist wizards, or Odinic sacrifice wizards who gain knowledge other wizards can’t via ritual and sacrifice, or really a death magic Wizard (only have the necromancy school Wizard, but controlling undead ain’t the only avenue of death magic), or a Spellcasting focus item focused Wizard with Totem style choices between focus items to...focus on (or a set of traditions, one for each of the wand, staff, etc), or a weapon based Wizard that puts their power into a weapon that becomes magical and grows in power with them, storing spells and unleashing them with attacks, or a golem-master, and I’m sure I could think of more.