I would prefer a world where no one would have to killed for peace. But I realize that this is also an impossible ideal for mankind, edit: Under normal circumstances. Something extraordinary would have to occur.
Light realizes that by using the death note he can become the justice this world needs. Honestly it does get a little out of hand by killing innocent people. It only became necesarry to kill innocent people because they tried to ruin Light's plans. Without anyone interfering with his plans, such innocent people wouldn't have needed to die. Light's way of justice may not be moral, but neither are any of the wars going on, and the murders, and crimes. Light's way of justice when compared to all that, imo is a much better solution and could possibly eventually lead to everybody being genuinely nice to everyone and helping each other out instead of killing one another.
From my view, L and friends stopped the worlds salvation.
In regards to the ending, Light's ***** was dumb as ****.