So it occured to me that restoration and necromancy could be thought of as just one school, working in opposite directions, with each end meeting at the same goal, which is to erase the effects of time on the body and to maintain the unity of its soul / life force / whatever.
I like to think of them as one school mainly because they are pretty much equal in how well they achieve their goal, which is always somewhat imperfectly. I remember in the story where the Emperors son duals the Potentate's son, his gaping wound is tended to immediately and healed. But after the attempted assassination of Emperor Reman III as told in Hearth Fire Book Nine of 2920, "despite the best healders in the Empire, it ( the Emperor's wound) was still a ghastly souvenir..." So there are limitations to restoration. Likewise, even the most skilled necromancer can only achieve a semblance of life, but can never fully restore what has been lost. We see this in The Exodus, where the daughter is indeed brought back to life, but only as a doll-like apparition (I remember the parents are horrified).
Another link between the two schools is that both Arkay and Mannimarco are said to be mortals who achieved their own divinity. In believe this represents our potential to actually attain, at least partially, the goals of both the restoration and necromancy schools; or more accurately, the restoration and necromacy schools now exist seperately as they do because our knowledge is them is incomplete.
To me, Arkay represents our potential to rid ourselves of disease, injury and general imbalance. I believe Mannimarco represents a much more ambitious, though no less noble goal, which is the overcoming of the barrier of death itself, though this may require the sacrifice of other, lesser life. This does not sound as bad as it seems, because smaller life forms can adapt and trasforms to suit itself to its host in mutually beneficial ways.
I like to think of this real world example as being the use of stem cells to regrown tissue. In real world terms, if I were a cell, would I rather decompose in some swamp, or live to become someone's arm? In TES, if I were the disembodied soul fragment of the most limited life form in all of Tamriel, isn't it better that my life force/soul is recycled to stich up a more sentient being's arm, becoming a part of that more sentient being, instead of hurling though the abyss with little to no awareness of my own being? If that is the case, then necromany is no better or worse than restoration, if the goal of both is to maintain the unity of your body and soul. You are simply stating your right to exist as you are.