You might be able to write a thesis paper on it, but I think it's one of the facets of the differing philosophies between the two universes.
Marvel, as we all know, has a long list of villains-turned heroes. Hawkeye, Black Widow, Quicksilver, Scarlet Witch (they never believed in Magneto's message or methods but they owed him their service because he saved their lives ... but they're complicit in destruction of what must be millions of dollars of US military property and the overthrow of a peaceful Central American government and the subsequent establishment of a totalitarian regime with Magneto as head of state), Swordsman, Medusa, Sandman, Sub Mariner, Vision, the Squadron Supreme (I think; I haven't read their introduction, but don't they start as Avengers villains?), the Thunderbolts, Gambit, etc etc etc
DC seems to have a much more deterministic view. There's a lot of crime busting and vengeance but not a lot of redemption. Heroes turn to villains but usually not the other way around. Look at Sinestro in the New 52, he's being set up as a hero but is anyone doubting they're going to turn him into the villain he is destined to be? The whole New 52 thing is actually kind of deterministic ... we are introduced to characters we know, some of whom haven't yet experienced things we know are destined to happen (because they're going to retell classic storylines).