Reason #1 to keep writing code by hand is that you don't ever lose that connection between you and the code.
There was an excellent post here on HN that unfortunately went unnoticed. I highly recommend reading it as it exactly points out this problem: understanding.
Here is the link: https://news.ycombinator.com/item?id=50128468
Note: The post has now been flagged. Why? I have no idea but it seems incorrect.
Because it's not glazing LLMs.
The post generated a mass of low quality comments (show dead). Plus after about a few paragraphs the site posted degenerates into just calling all AI companies liars with no (in-blog) justification.
I thought the flagging was appropriate after I read it.
Flying monkeys, probably. You can email hn@ycombinator.com about unwarranted flagging.