I'm not talking about abusing bugs and glitches here. I'd also never enchant for 100% casting cost reduction, since that would feel like cheating and make the game incredibly boring.

Assuming I'm building some kind of a mage (probably gonna use the Better Magic mod then), and I'd obviously want some stuff to help me out doing what mages do. For example the best kind of Destruction robes (which have a much stronger effect than what you could enchant something with, since it's hardcapped when using this effect for enchanting), some ring with magicka regeneration, maybe a circlet for Restoration (I kinda plan to use wards), and so on.

Now, let's take magicka regeneration for example. According to uesp, the base magnitude (with a grand soul) is 20% increased regeneration. The highest total multiplier I can get through 100 enchanting and all the perks is without potions 3.125 (with potions it would be 4.21875). This means that the highest possible fortify magicke regeneration enchantment I could create is 62.5% without and 84.375% with using potions (to fortify Enchanting). But (again) according to uesp, you can actually find rings in the game with fortify magicka regeneration of up to 100%.

So... why bother with Enchanting? Why bother leveling it up? Because of double-enchantments? That's pretty much the only reason I can see for doing so, since the magnitude of your enchantments is much lower than what you can find in chests, shops etc. after reaching a certain level.

I know Enchanting is meant to be the mage crafting skill, but I actually find it way more useful for characters who are, well, anything but a pure mage. That said, for a squishy mage, a boost to Stamina can be jolly useful for running like the clappers if you get into a tight spot, and there's magic resistance, plus having magicka absorb on a backup dagger can be helpful if you run out of magicka in a fight. I think potions of Fortify Destruction are more useful than robes that reduce magicka cost, because the potions increase your damage, so you kill stuff more quickly. Although obviously they have a limited duration. I've not done many non-Destruction-focused mages, so I'm not sure what wins out of potions or cost reduction gear for the other schools.

Never used it myself really, game isn't difficult or complex enough to warrant it. But depending on roleplay style there could be some good reasons to use it, guess it just depends on build type. For mages generally the default robes are pretty good but you could enchant for some strong hoods and enchanted shoes and gloves.

Double enchanting for sure, and magic skills aside I can make better enchantments than I can find or buy.

Even on a mage character, I can load up my clothes with fortify magicka and magicka regen or a specific magic school, and then fill out the rest of the slots with secondary bonuses (muffle for sneaking, stamina and stamina regen for movement, one-handed if using bound swords, archery for bound bow, light armor if I wear some armored pieces) depending on how I want to play.

http://i77.photobucket.com/albums/j68/sitruc2006/ScreenShot22shoes.jpg

Good for making money, dual enchanted daggers and jewlery to sell, and reduce the cost of Magicka when casting spells, and strong potions to sell..... but you don't really need it to assist in the game, it's a fun and useful thing to be able to do, you will acquire a lot of enchanted jewlery which is useful during the game as well, or can buy it.

YES ITS GREAT!!!

As are all crafting skills, tbh. IMO, it levels up far better than Smithing does post 1.6

Absorb Health/Absorb Stamina are flippin amazing to have

I feel like the alchemy skill is more useful for a traditional Mage character, because a load of potent restore magicka potions can obviate magicka cost reductions. Not to mention all the healing, hiding, and protections. Enchanting seems really useful for warriors, and also sneaky types.