Im not really good at starting topics.
I usually dont have a lot of original things to say aside from a line or two that says exactly what I think.
Im good at looking at what people write and forming a reply, because then I have a base-line to know what Im writing about.

This is a topic I feel really strongly about though so Im attempting to give it a whirl and explain my position.
Bear with.

I feel that Skyrim magic is sorely lacking.
The best way to describe this for me is by explaining my established habits with the game.
I play Skyrim as a sneak-bowman.
In itself this isnt a problem and its a quite enjoyable playstyle for me, especially since I use vampirism to spruce things up a bit and introduce several weaknesses and strong suits. But that is beside the point.

The point is that in three games before this I played a mage, a pure mage, an Altmer mage.
I was very weak at first but had some misdirection and evasion abilities. I could teleport out, I could damage attributes, I could get creative. Endgame I was a demi-god and I liked that. Start out weak, get strong eventually, its all about the journey for me. Getting there more fun than having it.
And yes, tearing through mobs that would have murdelised me twenty levels earlier did feel rewarding.

Skyrim though lacks this thing that made me a mage, lacks what made me gain control over the forces that underly Tamriel, as all spells are basically a one-off and there is really no way to 'tweak' the system.
It even lacks a marked sense of progression. Low level spells are useful against low level mobs and then never used again.
Gone is my lovely fortify speed for those treks Id done a million times already and just wanted to leave the Khagouti behind me.
Gone is my wonderful damage speed for when I want to taunt an enemy and wax wroth at him.
Gone is my beautiful levitation that let me leave these gosh-darn friggin mountains under me and just get where I wanted to go instead of having to traverse the pre-made path every. single. time.

There is no way in Skyrim to go: Right, Id like a low-level, short duration, wide area fire spell that will aggro everything around me. Nor can I cast a short, high-cost paralyse to get me out of tight spot. Its all or nothing.
I cant turn an ally invisible, I cant buff an ally his swordsman skill. Nor my own.
Cant buff an ally his health, nor my own.
Remember http://www.uesp.net/wiki/Morrowind:A_Falling_Wizard? You could save him in Morrowind. Just cast a levitation or slowfall spell at him. Cant do that in Skyrim, even if we had the spells there would be no way to cast them on someone else.

Mages have lost the vast majority of their versatility and certainly everything that I associated with being a TES mage.
I used to research the arcane. I used to learn effects and devise my own spells.
Now, Im an apprentice. No matter if I can cast a level 100 spell, Im still an apprentice, Ill never learn to harness the arcane. Im always stuck with the few pre-made spells.

Skyrim has the base roots of what used to be TES magic, but it has all its branches cut off.

Dragon Age 1 at least allowed you to combine certain spells into wholly new effects, spells never became obsolete and they were always interesting.
A game made by a different company a few years ago has a better, more utalitarian, better balanced, more varied magic system than a TES game.
A decade ago that would have been high blasphemy.

So here I come to the end of my diatribe, thanks for bearing with.
My conclusion is that regardless of anything else I am simply not interested in a TES6 without spellmaking.
I want levitation, I want teleportation. I want attributes and more skills than a pitiful 18.
But I will settle for spellmaking. That however, is the line.

Spellmaking is a flagship feature.
Without spellmaking Arena is a slightly above-average dungeon crawler.
The lore came with Daggerfall. Without spellmaking, there wouldnt have been a Daggerfall.
It is a quintessential feature to many a fan including me and I just have to draw the line somewhere.
I love TES, I love its worldbuilding, I love its lore and I love its attention to detail.

But I need spellmaking or else its just not TES.

Yes, they need something at least. It's a sad day when TES is getting closer and closer to Fable...

I agree, they should have spell making in later games. The spells in Skyrim were okay, but very lacking.

Spell making and spell scaling. I agree OP they need to bring spell making back.

I can appreciate your love of spellmaking. I personally never cared for it after making a cool spell with several effects only to have it look like generic fireball spell #7. Though I do find your attributing the ES series success to that feature a bit over-the-top. Hopefully they bring it back for you.

Couldn't have said it better myself. The joy of being a Mage in previous games came from thinking outside of the box, and doing all sorts of weird stuff with spellmaking. The most satisfying moments never came from simply destroying the enemy with offensive spells. These satisfying moments were always the result of doing something silly with spellmaking, and reaping the rewards of your ingenuity - slowing down enemy melee fighters with Damage Speed spells, summoning minions while simultaneously levitating away, or even completely nullifying the abilities of enemy mages with stuff like a 100 pt Spell Absorption spell that only worked for three seconds. Fancy effects and dual wielding of spells can hardly make up for such an important feature.

I've never been a fan of spellmaking myself.

1) The way magic costs/skill requirements are calculated make spells far too difficult to abuse

2) It's fun (in Morrowind especially) to travel around and find different spells for sale in different places, rather than just whipping up the "perfect" spells for yourself right away.

That said, the spell selection in Skyrim is incredibly bland. In Oblivion they took out spells from Morrowind that didn't work. In Skyrim they took out spells from Oblivion that DID work.