Why was the Holy Qur’an concluded with the two Surahs of refuge (Al-Mu'awwidhatayn)?

The arrangement of the surahs in the Mushaf is tawqifi (divinely ordained), and it corresponds to what is in the Preserved Tablet. This arrangement has meanings and connections between the surahs, including the suitability of a surah's opening to the conclusion of the one before it. Al-Suyuti mentioned examples of this, and some reasons for the tawqifi arrangement: according to letters, or for the agreement of the beginning of a surah with the end of the one before it, or for linguistic balance, or for the similarity of a surah's sentence to another sentence. Perhaps the conclusion of the Quran with Al-Falaq and An-Nas makes a person feel that they are exposed to evils from which there is no escape except by seeking refuge with Allah the Almighty.