Maybe we do different things. Not that you are wrong about spending less time on things that you don't care about, but at the same time all that mechanical things helps you build a really good mental model of your product from high level design to individual classes. If I already have a good mental model of that I can direct AI to make really good changes fast, if I don't I will get things done ... but it does end up with less than ideal changes that compounds over time.
What you said: "figure out how to do unfamiliar thing" -- is correct, and will get things done, but overall quality, maintainability or understanding how individual pieces work...that's what you don't get. One can argue who care about all that as AI can take care of that or already can. I don't think its true today at-least.
I guess I just don't really agree that doing the tedious mechanical things is all that helpful for building the necessary mental model. I mean, I do think it was useful (indeed, necessary) for me to actually type out very similar lines of code over and over again when I was building up the programming skillset, but I really think the marginal value of that is just very low for me at this point. I worry a lot about how we're going to train the next generation of people without there being any incentive to do this part of the process! But for me, I already did that part.
What I find is actually necessary for me to have a mental model of the system is not typing out the definitions of the classes and such, but rather operating and debugging the system. I really do need to try to do things, and dig into logs, and figure out what's going on when something is off. And pretty much always ends up requiring reading and understanding a bunch of the implementation. But whether I personally typed out that implementation, or one of my colleagues, or an AI, is less important.
I mean, I already had to be able to build a mental model of a system that I didn't fully implement myself! I essentially never work on anything that I have developed in its entirety on my own.