In responce to your 2nd argument. That is a subjective view. This is a single player game so there shouldn't be any issue whatsoever in worrying over destruction being to strong. You might have an argument over npc's however if you are playing a melee character but that's what modding is for. Besides, If this were a real situation, mages would pwn everything because it WOULD be that much stronger than anything else and rightfully so!
This is not a real situation, so ill just ignore that part.
I disrespectfully disagree. The issue is not so much about destruction being too strong, as it being too strong
-on its own- Let me explain:
Most people whine about warriors vs destro without reallizing something: that warrior has maxed a defensive perk (Armor), an offensive one (1h) and 3 for utility (smith/enchant/alchemy).
If Destruction is so powerfull that a mage could take JUST destruction and still be as powerfull as a full "warrior" build, it provides, therefore, about the same level of challenge in game.
Now what happens is that when you get out of the vacuum, you'll notice a lot of players will want to play with the other trees, the other skills. So you will have someone with full destruction AND full conjuration (say), way before being close to the game's ending.
Except that Destruction, by itself, is as powerfull as 5 other perk trees COMBINED now. So whenever you add anything to that tree, you are breaking the game and drastically dropping the challenge level.
In other words,
Destruction being too strong will break the game for those who wants to use it in combination with other trees.
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I still say
Magic needs to scale. Thats a priority. But passed that, you should have to use 2-3 perk trees together for the build to work. Asking to be able to ONLY use destruction is like a warrior asking to ONLY put perks in the 2h tree. Go try it and tell me, how OP exactly did you get?
EDIT: inbefore "Says who?!?". Well says the makers of the game apparently, otherwise they would not have designed it so that you only have enough perks in each tree to last you about 10-12 levels' of upgrading.