A few quests require you do things with a temporary follower who are part of the plot in the quest, there are dungeons puzzles you need to proceed to proceed. On a few them recalling out would cause that room to be locked forever. As you closed the gate when you went in and the switches are on the otherside.

There are also scripted events that may occur when you leave area, or fast travel markers that disappear because an event happen. LIke in a certain questline when you pretend to be a cook and then have to rush home when it all goes wrong. If you used recall, you'd end up in the original cell of that place instead of the altered crisis cell used for the quest.

That is all well and good, but that means that we now can get stuck in interior cells and be forced to reload.
That is what teleportation was most handy for, you cannot avoid areas of the map that can trap the player in massive games like these. There will always be oversight.

Provisions can be made to deal with these things.
It shouldnt be too hard to get the player to teleport to the right cell, just set it like that on entry of the quest cave.
In Morrowind you could not teleport out of the final fight with Dagoth Ur. I really wouldnt mind teleportation being limited like that if I can at least have it back.

I miss the constructed spells and enchantments where you could combine effects. And I do miss nighteye. I used to love that waterbreathing sense life helmet in Oblivion

I may be the only person that doesn't want nighteye to be a spell. I like it as a racial specific to the khajiits.

I do to, it makes me really considering being a Khajiit.

Feather, Levitate, Slowfall, Waterwalking: These could be made as a single spell actually, where you control high and low strength, and one or two handed. Strength is determined by skill, but wouldn't apply to learning rates unless in actual danger. For two handed waterwalking and levitate, it will still eat magicka like hell, but wouldn't really be a "flying spell", but might ease up on traversing some steep mountains without jump spamming the same amount. Works by taking off x amount of weight from you, and you can negate gravity barely only if you don't carry anything. High agile monks and light thieves would benefit most from it, heavy armor carriers wouldn't get any of these benefits (just be able to carry more). I really don't want the old flying stuff back, too high fantasy for me. But I'd prefer buoyancy (you sink quicker and swim slower the more you carry) over water walking, which have no purpose anymore due lack of underwater fighting, unless some kind of hardcoe mode adds hypothermia and water as a multiplier.

Open lock:- Not needed, since you're no longer required to open any locks. If only for utility rather than need, then it makes sense to me to separate it into thievery and make that arche type stronger than "mages that can do absolutely anything" - that's the part I really didn't like about previous TES, mages had no limits whatsoever.

Nighteye:- Makes you wish you picked that race. But seriously, why would you even want it or need it? In 99% of the time, it's bright as day in the deepest places, which kinda svcks. In Skyrim, I have never used a torch, light spells, or even used night eye for my test Khajiit.

Mark and recall:- To me these tended to make gaming cheap and easy. If they were in, I'd prefer it if radius was determined by your skill, and that dungeons was less frequently designed around having an exit immediately near the entrance. Still, I'm more a fan of the intervention spells, as you rarely knew exactly where you'd end up - could be some place still hostile

So far I'm pretty impressed with the magic system. I never liked magic before as it didn't make me unique in any way, it only allowed me to do everything else others did but cheaper (due regeneration). So for that, I enjoy that magic has things that are completely unique to magic users, and that I feel somewhat limited by not being something else.

Another one here who wants mark/recall.

I would also like the bound armour spells reintreoduced.

Another one missing is charm. But then again, disposition seems to be missing altogether as far as I can tell. Used to love having a low charisma, but charming them with my illusion spells

Poison spells (I know I can poision through alchemy, but no longer can through spell casting).

Slowfall I miss very much.

Silence

Shalidor's Mirror

At least 75% of the enemies wouldn't be able to deal with you in levitation if you fought them in conflict.

I want Morrowind's enchanting back.

Cast when used please.

Then that could have been fixed.
All (or most) humanoids could carry arrows.
In Morrowind I was once one-shotted by a lowly skeleton who just happened to have arrows of dispel.
He hit me and before I had realised my spell had failed or could even do anything I had fallen to my death.
If more enemies have arrows of dispel instead of it being random, you would think twice about floating over some mob.
It also really doesnt matter if wolves and bears and the like cant get at you.
Introduce some aerial enemies, like cliffracers only better implented.

All the missing Bound Weapons.. Seriously, why no Bound Mace or Dagger?
All the missing Conjuration Summons...
Feather...
Reflect Damage
Cure Spells

I like the new magic system and don't really miss some of the old spells. Too many of them could be blatantly used as exploits. I suppose Feather could be useful as a spell, but it made more sense in MW and OB, where you couldn't move if you were over encumbered.

Levitation doesn't work on the current world design.

Open Lock could be interesting for pure mages, so I wouldn't mind it. But it would mostly be for RP purposes, because the lock picking ability is already easy enough, so who would actually learn a spell limited by skill levels, when you could just use a lockpick?