For the sake of comparison, let's compare it to the closest mundane skill to Destruction's purpose, Archery.
They both have the primary purpose of doing damage at range, but archery completely blows Destruction out of the water.
Archery has the following things that Destruction lacks:
Critical hits.
Sneak attack if stealthed (and a stealth perk to increase the damage of these)
Fortify damage enchants and potions.
Perks to increase attack rate, zoom in to improve aim, and 50% stagger/15% paralyze per shot.
+100% damage perk (for 5 talent points - Destruction has +50% damage perk for 2 talent points, but split into 3 damage type branches.)
And finally, you can further improve bow damage by enchanting for extra damage, smithing and getting better arrows.
The only thing destruction gets is the aforementioned +50% damage in each branch for 2 perks each, and upgrading to better spells (think of it as the equivalent of getting a better bow, but not smith-able.) Destruction enhancing potions and enchants only lower the cost to cast. They do not increase damage or speed up attack rate.
A fully perked archer with full archery enchants can annihilate just about anything before it can reach him short of a dragon. A fully perked destruction mage with full destruction enchants is lucky if he can take out a Troll before it's whacking him over the head, never mind giants.
What destruction needs is something to compensate for the head start mundane combat skills have by having enchant-able weapons. At the very least, Fortify Destruction should enhance damage, NOT lower casting cost. It's silly as it is now anyway...you can reduce your casting cost to zero, but due to the casting time restriction, you still can't do enough damage fast enough to compete with mundane attacks.



