There has been a lot of discussions about overpowered crafting skills and I will attempt to explain the real reason behind these effects that you get in the game, at the same time I will demonstrate the mechanics that makes destruction weaker in comparison to other damage dealing methods.

The real mechanic behind it is STACKING:

If you place smithing next to say one-handed, it doesn′t seem overpowered...the added damage of finely crafted weapons is rather well balanced compared to the bonus damage of the one-handed perks. But here′s the thing, you don′t have to sacrifice one in order to have the other, what happens is that you have BOTH smithing and one-handed. If you then add sneak and enchanting ontop of that you get 4 damage bonus perks that stack upon each other. There′s no reason why I shouldn′t pick all 4, other than simply nerfing a character for roleplaying reasons, they combine for a better build and the main mechanic that drives players in a game is the desire to get better.

This is also why destruction ends up way behind other combat forms, because I can only stack destruction with enchanting, and enchanting doesn′t add any damage to destruction, only lower spell costs, whereas it adds damage to melee and archery to stack with the other damage bonuses.

The problem isn′t in the perks themselves, which do seem to have a built in balance when compared directly to eachother, the problem is that I can have them all and that there are so many skills that combine for effective melee combat. If I build a melee character there are so many skills that I can ignore that I don′t need to worry about not getting all the perks I need by maxing out in smithing and enchanting so there is no reason not to. What the mechanic needs is something which somehow restricts the options of perks so that I can′t have everything in the smithing, enchanting, sneak and one-handed tree at once. The mechanic must force a choice upon the player where maxing out in one skill means losing potential in another, as long as I can have it all, it is obviously the best strategy and leads to overpowering combinations.

I disagree with Destruction being behind combat, if you get 100% Magicka Recovery Rate you can launch lighting spells all day and Impact is very useful.

As to the rest, I don't see the crafting skills as automatic overpowering, the only time that I would consider them overpowering is if you use it as an exploit like fortifying smithing, Enchanting, Alchemy over 100.

I don't really agree with that.

You want to put more coded limits on the player. Now even though that might suit your play style it might not suit someone else's play stile. Personally I do limit myself, but I do value the fact that there is choice, choice to build whatever character you like. Your chain of thought would limit that choice.