Simply amazed at how badly you're missing the point. No-one has said Conjuration, Alteration or Illusion are underpowered. The issue is that Destruction, as a DIRECT-damage magic school, is vastly underpowered by comparison to the other (non-magic) DIRECT-damage skills - namely, Archery, 1-handed and 2-handed weapons. Completely ignore support magic for a moment, and consider the following scenario.
Character A has full, perked Heavy Armour. Therefore he is defensively in good shape. For attack, he uses a fully-perked battleaxe, with +damage enchantments.
Character B has full, perked Heavy Armour. Therefore he is defensively in good shape. For attack, he uses Destruction magic, with -magicka cost enchantments.
Character A will do a HUGE amount more damage than Character B. This is cold, simple and pure fact. Read the following:
Seems like a simple issue to spot - There are essentially 4 ways to directly do damage in the game:
1 - Archery
2 - 1 Handed Weapons
3 - 2 Handed Weapons
4 - Destruction
Sure, Conjuration and Illusion give you mechanisms by which damage can be inflicted, but you're not the one doing it directly.
First Perk of Archery, 1HW and 2HW is a 5 rank increases damage by up to 100% perk. First Perk of Destruction is a 1 rank reduces magicka cost perk. Destruction need 6 perk points spread across 3 perks in the middle of the tree to up Frost, Fire and Shock damage by 50%.
As your Skill increases in Archery, 1HW and 2HW, your damage goes up. As your Destruction Skill goes up, your mana cost by spell is reduced.
Archery, 1HW and 2HW can get a new weapon that increases their damage potential. Destruction has a limited spell spell selection, and does not have higher level versions of the same spell.
Archery, 1HW and 2HW can use the Smithing Skill to create and enhance their weapons. Destruction can not.
Archery, 1Hw and 2HW can use the Enchanting Skill to directly enhance their Weapons to do more damage. Destruction can not. Enchanting can be used to enchant other equipment to also enhance damage output for Archery, 1HW and 2HW. Enchanting can be used to enchant other equipment to increase Magicka regen and reduce Magicka cost for Destruction.
I could go on but I believe this list covers the main reasons why Destruction falls behind. Archery, 1HW and 2HW can all have their damage enhanced in a multitude of intuitive ways, and they all stack. Destruction has very limited ways to increase its damage potential, and it simply can't keep up with the weapon based skills in terms of sheer damage output.
My fix -
As your Destruction skill increases mana costs go down and damage goes up.
For each "Rank" perk (Novice, Apprentice, etc) mana costs are halved for that rank and damage of all Destruction spells goes up by 20% (stacking up to 100% at Master Destruction).
I would leave the element specific +50% damage perks as is.
Even with all this, I'm not sure Destruction would keep up with the extreme stacking capable with Smithing, Enchanting, Alchemy and a Weapon based skill, but I think it would definitely narrow the gap for most people, and be a whole more intuitive. You could use Alchemy and Enchanting to help boost your Destruction by a bit for more Damage, like you can with a Weapon based skill, but you still don't get direct enchantments on your "weapon" and you don't get new higher level versions of the same spells like you can with weapons.
THIS is why people are complaining. Not because
mages are underpowered, because as you say, they can complement their playstyle with several other useful skills, like Conjuration, Sneak, One-handed, Archery, with whatever the hell they want. The ISSUE, and the reason the game is unbalanced in favour of melee and archery, is that Destruction does FAR LESS damage than the other DIRECT damage skills in the game. Whether or not other spell schools make up the difference is completely irrelevant, seeing as any character, mage, warrior or thief, can also take those skills. The simple fact is that Destruction falls far behind as a direct-damage skill; for that reason, if you want to play as a pure mage, you are FORCED to focus on indirect damage (see: Conjuration) or to stop being a pure mage by focussing on other means of direct damage (see: Archery, melee weapons).
The (very simple) solution is as follows:
There's clearly a graded damage curve for bows and melee weapons, whereby increasing your 2-handed weapon skill from 20 to 21 makes your battleaxe do a little bit more damage, and a battleaxe will do a lot more damage with a 2-handed skill of 100 than with a skill of 20, even without any perks.
Why can't the same system be applied to all spells? So (pulling numbers out of thin air here, just placeholders):
- Flames does 8 DPS at Destruction 20 (pulling numbers out of thin air here) but does 40 DPS at Destruction 100
- Summon Familiar summons a ghost wolf for 30 seconds at Conjuration 20 with an attack rating of 10 and armour rating of 20, but for 150 seconds at Conjuration 100, with an attack rating of 50 and an armour rating of 100?
It seems so obvious to me, but what do I know...
The extra "exploitative" damage achievable through Enchanting and Smithing could be balanced by introducing +Destruction damage/spell effectiveness/duration enchantments, which could then be stacked to make Destruction have the same sort of damage potential as Archery or melee.
Finally, please don't argue "I've played as a level 50 mage and I'm fine, so you're all wrong." This is a completely moot point unless you've also played as a level 50 warrior or assassin, at which point you would realise how much more powerful melee and Archery are.