If I pile a bunch of rocks high in the sky and call it a skyscraper, that's creating order from disorder, but isn't "negentropy." Similarly, the sun has been shining on our planet for at least as long as life has been on it, so invoking thermodynamics is kind of out. The question of why still remains, though. Presumably I built the skyscraper because someone paid me to do it, and if I get paid to do something then I can use that money to... see where I'm going? Anyway, it's perfectly reasonable to me to imagine that any replicatory process would generate better replicators, and DNA is quite good at what it does. There's no reason to assume that it popped out of nowhere, or was zapped into existence after a lightning strike - there is, as you point out, every reason to assume the opposite. None of this rules out the possibility of simple replicators leading inexorably to more complex and efficient replicators, but it's when we have no reason to believe that DNA was the start of everything, it's cheating to point to the middle of the process (DNA) and say, "How'd that get there?" (to quote an awe-inspiring man). Heck, I'd look to the RNA World before I asked that question, but I think there's probably something even simpler before that - that's the fun of science!