I bought Tasha's primarily to unlock the new summon spells for my sorcerer, but they're arbitrarily disallowed for the sorcerer despite the wizard and warlock (the other non-divine casters) getting them - pretty disappointing to be honest. It was already a let down that Animate Dead isn't on the sorcerer spell list in 5e despite being on it for 3.5 

Please consider changing this

Looks like Aberrant Mind Origin gets summon aberration, Clockwork Soul gets summon construct, and Divine Soule automatically gains access to the Cleric spell list for summon celestial. The intention seems to be to give Sorcerers thematically appropriate abilities.

I'm sure there will be an update that will eventually grant the other Origins their own expanded spell lists with the appropriate summon ability.

Wizards obviously have the most expansive spell list, so it makes sense for them to have access, while Warlocks have a unique flavor along with their own limitations. Sorcerers explicitly draw their power from a supernatural magical origin that restricts the type of power they can control. A shadow sorcerer summoning elementals and joyful fey spirits would be discordant.

I get that a lot of the flavor for a sorcerer can and should come from their origin, but wizard's versatility has traditionally come from them being able to prepare a new set of spells entirely for the day, while sorcerers learn spells and are locked into them. For example, if a wizard knows they're about to go up against undead, they can prepare an entire set of anti-undead spells the night before. Restricting the Sorcerer spell list in addition to that seems unnecessary - in previous editions the aforementioned key distinction between the two classes worked great.

Also, DnD is all about customizing your character! Sure, one sorcerer might be a Divine Soul but that background doesn't necessary need to define their every iota of existence. It'd be a little boring for a Fire Draconic Bloodline sorcerer to have only fire spells, for example - versatility is the spice of life!

Sure, and that's where House Rules come into play. Everything in Tasha's, including the spells, is explicitly optional. If you want a spell on your list that is outside of the "standard" ruleset, then you and the DM have the option of making any changes you would like.

However, the Sorcerer ultimately gets around a lot of their limitations though Metamagic. Specifically, the new Transmuted Metamagic option effectively gives sorcerers a whole ton of combat flexibility. Any spell you can cast can be modified to deal any elemental type or poison damage, at the cost of a 1 Sorcery Point, which is pretty awesome.

It sounds like your contention is specifically with the availability of Summoning spells, which represent a very specific magical niche, and in some editions/games turn into their own class entirely. Animating the dead, in particular, is a very thematically polarizing concept that is typically associated with "studying dark secrets" (Wizard/Eldritch), or manipulating Life/Death (Divine). A sorcerer can be many things, but a gold dragon descendent sorcerer discovering the ability to animate the dead would be pretty random and inexplicable.

Very few magical origins include the ability to summon, broadly speaking. Demons can summon demons, and Beholders can create strange things, but otherwise, the standard options are pretty limited. However, you might be interested in designing your own sorcerous origin that specifically opens up Summoning. For example,

Sorcerous Origin (Storyteller)

Somewhere in your lineage is the influence of a being known only as "The Storyteller". This being was said to travel from tavern to tavern telling stories, the words of which would cause the very air to ripple, taking the shape of beasts and blaze alike. Epic tales of forgotten conflict would manifest before him, thrilling and terrifying those captivated by his performance. As quickly as they appeared, his creations would vanish; like a book slamming shut, trapping the words within.

Then just add the summoning spells to your spell list, and balance it with appropriate class features. This would read kind of like a Sorcerous "Bard", as opposed to a Sorcerous Cleric (Divine Soul).

It seems they didn't want these summoning spells to be available to any and all sorcerers (which I get, it isn't really in flavor with them as a whole), but they gave specific subclasses an appropriate summoning spell. This also makes sense.

The problem is, short of reprinting the entire subclass, they can't just errata a subclass printed in another book to have new spells. But if you want to homebrew it, it makes sense for the following subclasses to get the following spells:

• Shadow magic : summon shadowspawn
• Storm sorcery : summon elemental
• Wild magic : summon fey

I've wanted to be some kind of summoner when I decided I also wanted to be a sorcerer. After much digging, I found out recently that if you take the Variant Half Elf race that includes the Mark of the Storm, you get a number of spells added to your spell list which include Conjure Minor Elementals and Conjure Elemental! I took both but that way it gives you the option even if it's only available for half-elves. Being a storm sorcerer on top of that, I HAD to take this so I could summon elementals but it would still seem thematically appropriate. Happy Summoning! :)

Quote from ThirdMarshall >>

I've wanted to be some kind of summoner when I decided I also wanted to be a sorcerer. After much digging, I found out recently that if you take the Variant Half Elf race that includes the Mark of the Storm, you get a number of spells added to your spell list which include Conjure Minor Elementals and Conjure Elemental! I took both but that way it gives you the option even if it's only available for half-elves. Being a storm sorcerer on top of that, I HAD to take this so I could summon elementals but it would still seem thematically appropriate. Happy Summoning! :)

 That's fine and a good way to get around some limitations. Eberron and Ravnica both have means of expanding class spell lists, but it wont be welcome in every setting so do keep that in mind.

I wonder if they held out on giving base sorcerer summons in order to leave room for a sorcerer subclass that specialized in them. That would be pretty cool to see.