A significant component of the evidence offered to support this theory is that life seems to have appeared so early on in earth's history that a molecular structure such as DNA—which is a highly evolved and optimized molecule that must have undergone millions of years of evolution to attain its present level of sophistication and efficiency—couldn't have had time to arise and refine its abilities.
Earth, after all, is presumed to have been a hot, molten ball of fiery magma for much of its earliest history, with properties that preclude the existence of life in any form, even that of extremophiles. The earlier that evidence of organized life turns up, the more likely it is that panspermia was the source of that life.
Now a new discovery has pushed the origins of life back even earlier than expected. This is pretty cool stuff, making it more and more likely that the fundamental building blocks of earth's life originally arose on another planet... more than likely, even another solar system. Life may be a heritage that dates back to the first billion years or so of the universe, when galaxies were still forming... in which case life is approaching 13 billion years old, or something like that. Given the propensity for carbon to be the arbiter of all organic chemistry, that life may well have been DNA based... at which point we would have to say (I think you can see this one coming) that life is built into the very DNA of the universe.
Of course, all kidding aside, this would be miraculous news indeed. If DNA based life is indeed an integral and inseparable part of the universe's character and nature, it carries what are perhaps nearly metaphysical implications.