In the superflat customization screen, more specifically the presets list, the box to enter in a custom preset is labeled "Want to share your preset with someone? Use the below box!". As the "Add Layer" and "Edit Layer" buttons did not end up being added, this label is misleading, as it is much more commonly used to enter a custom preset, in which case you would already know the code if you wanted to share it with someone. The only real changes you could make where you wouldn't necessarily know the code are removing layers, and there's not much room for customization there. Also, it would be easier just to tell someone to select a certain preset and remove a certain layer than to give them the code.

A better label for the text box would be: "Enter a custom preset code here: (for advanced users)"