With this reasoning I can be a Destruction + Conjuration mage able to summon Daedric Dremoras and then bust out master level destruction spells without needing to drink any magicka potion, use any restoration spell because my Dremoras be taking all the beating for me, and smash through any enemy in the game regardless of skill level and size.
You, uh .... haven't actually played through as a mage to confirm that it goes as smoothly as your comment here suggests, have you?
FFS. Is it really too much to ask you actually try it yourself before you condemn an entire build as OP? Independent verification and all that....
Because I would have little use for more magicka I can now dump the rest of my perk points into my health and stamina, accompany this with a high level alteration mage armor spells and I can have the skin of a dragon with nothing but robes.
Uh... again, did you actually play it through like this for yourself? Considering what you describe requires that Enchanting, Destruction, Conjuration and Alteration all be at 100 skill level to do what you're suggesting, you would by necessity be level 32 even if you somehow did absolutely nothing else--never opened a locked door or chest, never talked to a shop or spell vendor, etc. With even modest increases in Speech and Lockpicking (to be expected if you plan to over bypass a locked door or chest and hope to ever sell anything, ever, to any vendor), from 15 to 30, you're now sitting at level 36 with this build. Even if you took increases in magicka over health and stamina at every level up to that point, you're at 450 magicka. Total. At Alteration 100 skill, the cost of Dragonhide is 494 points, or 247 with the master-level cost reduction perk. And it lasts for ... 30 seconds. 45 with the Stability perk.
OP. Uh huh...