I just bought an ultrawide, and I just checked to see how wide my lines are in my code editor. 350 characters.
When I'm coding for myself, I use all of that at times. I love that there are some things I no longer have to break onto multiple lines any longer.
Also, if you have a ton of nested loops etc, then you don't end up with that problem where you can only see the first few characters of the deepest lines.