This is not true. With 100 enchanting, and the perks you get 25% cost reduction enchants and can apply one to each: ring, necklace, helm and chest. This causes 100% cost reduction without looping or exploits or anything fancy.
Removing can be the best option. Such is the case of the following: Alchemy enchants, Smithing enchants, Enchanting potions and Smithing Potions. It's virtually impossible to keep these balanced because they feed each other and the only thing keeping them in line right now is that the game always rounds down(which the resto potion trick gets around). Other things can be fixed and typically trying to ensure more choice is a good idea but there is a difference between unbalanced and broken. Unbalanced is fixable with small number tweaks. Broken is an inherently bad design that needs to be redesigned or removed as it cannot be balanced in it's current form.
Here is are some examples with some arbitrary numbers that could help fix some of the problems with mages:
-Limit what impact can stagger(bosses or close to it should not be staggered). Limit duration on illusion control spells, especially on boss types.
-Lower mana cost on spells by 50% (spell costs right now without the perks or enchants is just obscene...)
-Change fortify
-Change perks from cost reduction to increase damage/duration
-Lower base spell damage and add increased damage to the base skill (more damage as you level up destruction)
-Ensure each spell would fill a niche and is viable throughout the game: novice spells for efficiency, apprentice for everyday use, adept for area of effect spells, expert for inefficient but very high damage spells
-Add +magicka to ALL cloth(in lieu of armor) and still allow additional enchants
-Increase magicka regen in combat to 50%
-Add perks to allow further magicka regen in combat(perhaps alteration tree?)
-Modify enchant power: full effect on cloth, 85% effect on light armor and 75% effect on heavy armor
-Remove increased mana cost for dual casting
-Alteration flesh spells should last a long time(~5 minutes base up to say ~15 minutes with stability + dual cast)
-Master spells need: reduced magicka cost, dual cast bonus and increased effect(or reduced cast time)
-Introduction and heavy encouragement of enchanting while doing college quest line.
-Introduction of enchanting NPCs that can add enchants to your gear for a price(less effective than fully level and perked custom enchants)
(I'm not too sure on how to deal with conjuration very well yet)
At the end of the day unless you were previously using 100% cost reduction enchants this will make you much more powerful. For those that were using the 100% cost reduction it makes the game much more challenging but fixes many of the common complaints like spell scaling or the shady enchants and it would make things much more intuitive and encourage a more "standard" mage like those at the college while not removing other options. While it may seem like a lot of changes it's not really that big a deal but it does cut off that upper most limit of power that is just way to ridiculous(100% cost reduction to endlessly spam dual casted spells to proc impact) and also ensures that magicka matters and is manageable and more intuitive. This effectively lays the groundwork for being able to properly balance enemies to fight against you since the range of power you'll face from a player that's a mage is much smaller unlike now where on one end you have borderline worthless to gamebreakingly powerful.
Of course mods will fix this for people on PC(like myself) but as I've said before I can't just sit around and continue to let developers set the precedent that it is ok to rely on modders to correct glaring design failures. That's not right.