New here....couple of main points.
1. Fine tuning is a scientific concept and theory. I think IDers use it to say intelligence exists that is involved in ordering the universe and I think the science suggests that they are right.
2. On the other point that somehow this is throwing the God of Abraham under the bus, you make a very common error and interject a theological argument into the science. You presume to know what God would be like as a Creator and to understand His purposes and think, well, He wouldn't do it that way. He would surely not use the same DNA, or another one evolutionists often come up is that He would surely design things more perfectly. Of course, if He did that we would never have something called human beings but that doesn't occur to them.
Strangely, those critical of Intelligent Design theorists and others often come up with theological arguments as one of their basic evidences and yet constantly say IDers and creationists are inserting theology into science, but really they are generally sticking to the data and science in their explanations of things.
On the similar DNA and why God would do that, there are numerous reasons why that we could come up. One could question why animals all have similar physical properties. I mean why shouldn't some creatures be made up of light, and what's with having the whole universe run on the same math. Couldn't God in His infinite creativity had some worlds, for example, like the Lewis tales where you go into a closet and come into a different world. I mean it's like He's just not creative. Why do we always have to travel through space. Couldn't he do better than that? Even Star Trek creators imagined being able to teleport around, and the author of Dune had that spice thing that enabled one to transport to the other side of the galaxy.
Wouldn't that be cool?
Is the argument? I just don't think God exists because He didn't design the universe as wild as we would?
And yet, the universe is pretty far out. We are learning more mysteries all the time.
On DNA, perhaps He used DNA across the board so we'd better be able to understand it and progress in our science? Or, He just felt like it? Or, when He created, that aspect of creating embedded itself into the universe and so the process itself dictates the similarity.
Could be a bunch of things. Certainly the Bible says information outside of space-time or a layman's concept of "physical" is the origin of all things. The Logos or Word lies at the heart and origin and root of anything. Maybe information itself needs to be connected together throughout the universe and this is why math works so well, and this is why life has a similar information sharing system?