All of the OP's statements are true but also not true. For example: law is about authority, computers reject authority. What is authority? In some sense, it's just network effect. A sufficient number of people have agreed on an argument, therefore it won't be disturbed unless there's a very good reason. Same goes with computers.
Innovation vs. Applying past wisdom: The law's not so myopic to only look to the past. It considers the accumulated wisdom of the past to determine what to do now. In fact, the law is changing rapidly in part in response to technological innovation (and the increasing complexity of government and modern life). The question is whether past rationale makes sense under current conditions. Under that frame, innovation and disruption happens in the law -- consider the law & economics movement, for instance, or critical legal theory.
The question isn't whether law or programming is inherently more innovative, it's where you're situated.
If you're arguing cases before the Supreme Court, you are dealing with the cutting edge of law and you are constantly looking at new cases that come out and analyzing how their rationale opens up new arguments and reflects new ways to attack existing decisions. The problem is that to do that, you have to be the best of the best.
If you're a programmer at a huge corporation working on maintaining a legacy system, you probably think you have the dullest job in the world in a field where nothing changes.
No doubt, real differences exist between law and programming, although they are remarkably similar. Nevertheless, I think Newport is on point when he talks about just how important excellence is to appreciating and enjoying your craft.