oh wait, what's http://en.wikipedia.org/wiki/Sacred_geometry?

And it's been wrong ad nauseum.

Spellmaking only affected spell effects that were already in the game.

Fact.

Cannot be disputed.

It did not create all new effects that weren't already in the game.

No, and we've been through this even before the game release. You like to ignore things that prove you wrong though, so obviously you'll never acknowledge the proof and examples that have been made ad nauseum. No need to quote me anymore though, I couldn't care less what fan boys think.

You could create spells based on how you wanted them.
You can crisscross effects to make what you want.
You could make what you wanted to with what was in the game.
It simply added options and customization.

In Daggerfall you had to get pretty high in mages guild to make spells, you could not make them from start in Morrowind either as I remember, you had to do the introduction quests in Oblivion.

As I understand it was dropped so they could add cooler spell effects, very hard to combine Oblivion spellmaker with the spells in Skyrim.
However just an ability to set the strength of your spells had solved the entire weak destruction issue, yes the high powered spells would eat mana as crazy but that is your problem, this brings us to the free to cast spells.

Posted this in the other spell creation thread but since this is my thread anyway I might as well post it here.

Here is what I'd like to see for spell creation. First it would rely on something besides gold. Maybe Soul gems, maybe regular gems (diamond/ruby/etc) or something new entirely.

First you would select a spell effect (or effects)
Then you select the permutation of the effect, whether it's on self, a stationary aura, a projectile, a rune, or any other form that a spell can take in the game.
Then you would select an intensity (novice through master), no more selecting specific numbers.
Then if applicable you select an area (small medium large) and duration (short medium long).

I think this would let people use the spell creator to give their mages plenty of individual flavor while removing some of the gaminess and cheap exploitation out of the system.

But with the other system you had more control than with what you propose.
Its all about self control you do not have to make everything super powered or under powered.

Gameplay mechanism, yes an actual npc you interacted with to create the spell like in Daggerfall and Morrowind feels better, this trained mage help you put together the spell so it have the wanted effect, you could actually make this totally dialogue based but it would be less user friendly.
Enchanting makes more sense using some sort of device, an npc would here only operate the device for you.

Popular spells are spells who cost less to cast than your custom spells, someone figured out sweat spots who was cheaper or special ways to cast them.
Naturally this spells become more popular, the main reason to create lots of custom spells in earlier games was to rename them so they was easier to find.

Or roleplaying value and mixing whatever you wanted together.