A simple suggestion, in my opinion.
Sometimes I may have a single-symbol symbology configured for a feature class, only to realize that I need to implement some categories/unique values. I change the symbology type, and lose all my settings I had on my original design as the software randomizes it for you. Maybe an option could be created where you can choose between randomizing the symbols or populating all values with your symbol (then you can make small adjustments like color/size to each from there).
Or better yet, changing from unique values to single symbol. You lose all the settings for each single category. I think at least there it can present the option to keep one of the symbols as you make the transition.