The Inheritance Cycle, from the three published books, appears to be buying into this theory hook, line, sinker, fisherman, boots and all. Murtaugh is harsh in the beginning out of fear for his life, not because he's a bad person, and he murders hundreds (semi-?) unwillingly because Galbatorix is forcing him to. The soldiers of the empire are similarly enslaved. Even Durza and Galbatorix are basically good. Durza, stuffed to the eyeballs with raging demons, is enslaved by them because he summoned them to avenge his dead master, and even the demons are raging because the can't bear to be stuck inside mortal flesh! (I personally did not understand how both parties could be guiltless in the transaction, but that might just be my failure as a reader.) Galbatorix was set off on his murderous rampage by the death of his dragon, which it has been hinted drove him mad (No sane man could do all that evil!).
On the other end of the spectrum, authors such as George R.R. Martin, and Vince Flynn portray all men as bad, their evil diluted only in as much as they have good motives. Their villains are vile and their heroes have some dark weakness, which is intended to bring out their 'humanity'. This end of the spectrum was occupied heavily by World War era writers such as T.H. White, George Orwell, and Kurt Vonnegut, whose message was something along the lines of 'Man is doomed, Humanity is coming to get us". As far as they were concerned, we didn't need alien invaders to destroy us, we were doing the job just fine on our own.
The great literary and artistic movement that couldn't stand Aragorn (he was too perfect), Sauron (he was two dimensional), or anyone from ancient stories (they are either good or bad, nowhere in between) has decried such literature because their character were either black or white, with gray left out of the matter. They thus set off to create characters who were more believable with plenty of grey areas, yet in their attempts to paint men as both black and white , they painted mankind one or the other.
Where Tolkien, Lewis, and authors of the past realized that mankind was gray and thus painted their characters as either black or white, Modern artists demand that characters be gray, and thus either condemn man to hell as a demon, or raise him to heaven as an angel.
Man kind is neither black nor white. He is a noble creature created in the image of God who feeds the poor, clothes the naked, and provides for the homeless. People such as Mother Teresa, Martin Luther King, and Gandhi exemplified the humble passion that is a characteristic of man, and it is such people that J.K. Rowling and most modern authors think of when they think of man.
Yet man is also a mean, twisted creature who will turn upon his closest friend and kill him for pleasure. Such were the German and Austrian Youth who murdered Jews they had known since childhood for sport. Such were the guards at Auschwitz, Treblinka, Sobibor, and Belzec who would make men jump to their depths for fun, hunt prisoners and snipe at them from guard towers. It were these men that T.H. White and Vonnegut thought of when they thought of man.
Yet this is not all, Man is also a conquerer who tames the wild stallion and forces the mighty bull to yield. Man is a creator who builds monuments to dazzle future generations, bridges that span massive caverns, and cities well nigh impregnable to assault. Man is a destroyer who will burn a painting hundreds of years old for a few moments warmth and burn a city because its people offended him.
Man is too complex to be basically good or basically evil, the terrible and wonderful fact is that man is both.
