Conditional Checkout Fields & Edit Checkout Fields for WooCommerce

For some reason, the placeholder field is disabled in the editor for the default fields. It’s possible to change placeholders of the default checkout fields via code, so I can’t understand why this addon won’t allow us to change them just like when adding your own fields. The documentation does not explain this, nor is there an explanation for it in the interface.

Any reason for this? Otherwise I think it would be nice if this functionality was added.