Magic is incredibly useful in Morrowind. These are just some of the spell effects I've come across.
You could:
Drain attributes (7)
Drain health, magicka, fatigue
Drain skill (27)
Resist all of the above
Restore all of the above
Fortifty all of the above
Damage all of the above
Fire/Frost/Shock/Poison damage
Calm Humanoid/Creature
Command Humanoid/Creature
Levitate
Chameleon
Invisibility
Fly
Telekinesis
Mark
Recall
Open
Lock
Summon Creature
Summon Bound (Sword, Shield, etc.)
Sanctuary
Paralyze
Water Walking
Water Breathing
Cure Common Disease
Cure Blight Disease
Cure Paralysis
Cure Poison
Light
Frost/Fire/Shock/Poison Shield
Almvisi's Intervention
Divine Intervention
That's about 222 different base effects just off my memory, and I'm not even that far into the game. Multiply that by 3 (yourself, touch, ranged), and then 5 (different casting triggers). Multiply that by the 10,000 different possibilities of power.
That's 33,300,000 spell effects you can create. Did I mention that when creating a spell, potion, or magic item that you can mix spell effects? I don't know the max, but I've seen items with three effects. Take 33 million to the 5th power and see how many custom spells or items you can make with the magic system.
Now compare that to a D&D magic system with something like 400 spells.