Magic is awsome and balanced. The people who complain about it are just silly people who want to run around one hitting the toughest mobs in the game. They are allowed there opinion if they want to play on easy, but i will be disappointed if bethesda gives in and break magic. I wish the whiners would just switch to easy mode and stop complaining. Just because melee can become broken when you min max does not mean we should break something balanced.
If you think this then you've never played a mage who uses both Destruction and Conjuration, and can see the vast gulf in effectiveness between the two at higher levels. Here a test which, if you have a suitable mage, should be fairly simple:
1) Find a barrow or other burial location
2) Find a Draugr Scourge Lord (will usually be at the back)
3) Fire any Expert-level Destruction spell, note the pitiful amount of the DSL's HP bar it removes
4) Summon a Dremora Lord and watch it obliterate that same creature
If magic were balanced, the Destruction spell would be almost as effective as the Dremora summon in the same time frame, and it simply isn't. Sure, you can stun-lock the DSL and whittle it to death, but why bother when you can kill it 10x as quickly with a summon? In stark contrast to this is what happens when that same DSL faces a high-level well-equipped Assassin using either a Bow or a pair of Daggers- it dies instantly, without knowing WTF just hit it. I can't speak for how a 2H or Sword+Shield character fares as I don't play them, but it's likely to be a fairly short fight.
Unless you meant globally balanced, in which case you might be right, since the top-end summons are pretty powerful, especially in pairs. I doubt it, though, since you cannot massively boost Destruction damage the way you can Archery or Melee damage. Of course, it's hard to properly weight the relative safety of the stun-lock, since it can disable pretty much anything in the game but most folks probably can't juggle multiple opponents with it, so how broadly useful it actually is in practice is debatable.
That said, the case under discussion is Destruction by itself, and when stacked against Archery or Melee it's
way behind in terms of raw output, which is what we're trying to address.