As I learnt looking into the indicators the accessibility of traffic lights had a lot more to do with their vertical position than their colors. Can't use solid green, yellow and red if we want them to be understood by people with various forms of color blindness.

But you could make colorblind-friendly color schemes available through plugins instead of making a slightly more confusing option default.

Do you mean the weather icons? They are not the alternative to properly designed status indicators. Take a look at this https://jenkins.io/images/post-images/blueocean/pr-view.png

There's more about why and when we use them in my other comments.