Why are diligence and creativity accepted in fatwas, but not in supplications?

The door of supplication (du'a) is wide. It is permissible for a Muslim to supplicate to their Lord with whatever they wish, even if it is not from the transmitted (ma'thur) supplications, as long as they adhere to the etiquette and regulations of du'a. They should not supplicate with sin or the severance of kinship ties, nor should they transgress in their supplication by asking for the impossible or by excessively using forced rhyming prose. What is more preferable is to maintain the transmitted prophetic supplications.