I don't believe that "coding" is a single axis of quality, either. I'm now better at some types, and worse at others.

When I was young, I was much better at reading or writing complex functions that worked correctly. As I get older, I'm much less able to, but I also wouldn't want to even if I could.

I don't think that's just sour grapes. I don't want to inflict complex code on my coworkers, either. And there's many times (when I'm tired, when I'm fixing an emergency bug, etc) that I'm not at 100% mental capacity and I value not having to work right at my brain's complexity limit.

16 year old me would probably not have believed that.

At 50, I have noticeable fast and slow periods. But when everything is firing correctly the correlations and ability to quickly see the forest for the trees is better than at any other time in my life. People are also more interesting and I tend to enjoy each nice day a little more than the last. Most importantly for professional work I now know when to give up and move on or dig in and finish.

It is orders of magnitude harder to write a “simple” solution. Developers should not be proud of complexity at any age.

Are you suggesting one should be proud of something just because it's harder?

No, one should be proud of creating an elegant solution.

At 42 I feel like my coding gets better as my context increases. Getting worse with people though.