Why wasn't Surat Al-Isra named Surat Al-Isra wal-Mi'raj?

Scholars have differed on whether the naming of the Surahs (chapters of the Quran) is divinely ordained (tawqifi) or not, and the correct view is that it is divinely ordained. The names of the Surahs of the Quran have been derived from a rare or remarkable occurrence within the Surah, such as Surah Al-Baqarah (The Cow) due to the story of the cow mentioned therein, Surah An-Nisa (The Women) due to the mention of the laws pertaining to women therein, and Surah Al-Isra (The Night Journey) due to the mention of the Night Journey therein, and it is also called Surah Subhan and Bani Isra'il (Children of Israel). As for the Mi'raj (Ascension), some commentators mention that it is alluded to in Surah An-Najm (The Star), while many commentators believe that these verses do not mention the event of the Mi'raj, but rather refer to the Prophet's (peace and blessings be upon him) seeing Jibril (Gabriel).