I haven't read every post on the theory of Lavos and his motivations. So maybe I am saying what someone else has already thought of. But consider this:
Perhaps Lavos has a dream. A good dream. That once he collects enough DNA, he will undergo some sort of ultimate transcendent experience of time, space, and consciousness. That he realizes that all life, while unique and special in it's own way, is all pieces of a puzzle. And he has a dream of something glorious, a dream of what you get when you put the whole puzzle together. Perhaps he is a monument to all of the wonder and magnificence of life in the universe. And maybe he thinks, yeah sure, if you are going to make an omelet, you will break a few eggs.
Maybe, just maybe, if enough DNA is accumulated, he will have enough power to BE God. To remake the universe in whatever image he chooses. Since he loves DNA, and power, and life, he will remake the universe in the best possible way, to glorify and nurture life. Perhaps the original timeline, where he eats Earth and then some other planets, where he finally completes his transformation, is just a step in his process. Once he accumulates the ultimate power, he remakes the whole timeline so that he NEVER ate anyone, so that everyone lives the best and most fulfilling life that they possibly could. Maybe he is an aspiring Entity, with good intentions, who is misunderstood at a somewhat gruesome stage of his journey of evolution and growth.
Who knows. I was just thinking, a creature like that might have an agenda that would be understandable as a logical process, only it would be dealing with concepts and forces that would be near impossible for humans to understand. Perhaps on the level at which he operates, he actually has good intentions. Like trying to explain to your cat or dog why sticking a needle in them will do them good in the long run.
