What was Moshe worried about now? Of what importance was it to know the Name of Hashem that was currently relevant?
Ramban #1 (citing the Ibn Ezra): Should Yisrael ask, he wanted to know, which Name of Hashem to cite, because Hashem does not perform miracles with the Name Shakay, 1 only with Havayah (the Great Name of Hashem). 2
Ramban #2: Since Hashem had not indicated with which Midah He would appear in Egypt, Moshe wanted to know whether it would be with Midas ha'Din (symbolized by the Name Shakai), with which He wrought hidden miracles; or with Midas Rachamim (symbolized by the Name Havayah), with which He wrought open, supernatural miracles. 3
Ramban #3 (citing Chazal): With reference to Matan Torah, when Yisrael would ask for a more intimate relationship with Hashem, 4 he was now asking Hashem to reveal to him His Great Name, in order to answer them when the time came.
Seforno: A person's name reflects his intended 'format.' Consequently, if Yisrael would know what to call Hashem, they would know His plan of action. 5
Rashbam: He simply wanted to know Hashem's Great Name, 6 in order to answer Yisrael should they ask.
Rosh: Moshe wanted to know if he should tell Yisrael the Perush of His Great Name.
The Name by which He had operated with the Avos. See Rashi to 6:3, at the beginning of Parshas Va'era.
See Ramban's objection to the Ibn Ezra's explanation. Rashi (to 6:9) explains that Moshe was actually taken to task for questioning Hashem at all.
Ramban: What prompted Moshe to ask whether Hashem would change His tactics, was the fact that Hashem had mentioned Matan Torah - which he knew would not be performed with the Name Shakai that had prevailed in the era of the Avos, but with the Name Havayah, with which He had created the world. See also Ba'al ha'Turim; and Gur Aryeh (3:13:1.1:1)
See Rav Chavel's notes.
See Ramban to 3:12, DH 'v'Hinei.'
Presumably this refers to its deeper meaning, as the Ramban explains according to some of the explanations that he cites.
Could the Bnei Yisrael not have known the Name of Hashem? The Avos used it regularly!
Gur Aryeh (to 3:14): [Moshe said that the] Bnei Yisrael would ask with which Midah their salvation would come (for we refer to Hashem by various names, according to His deeds). If it would be with the specific Name (Havayah), they would be assured that it would be a complete salvation - and painless. 1
Maharal #1 (Gevuros Hashem Ch. 25, p. 106): Moshe argued that in order to draw close to Hashem and be worthy of redemption, one should know not only of Hashem's name, but also the hidden meaning behind it. Moshe said that the Bnei Yisrael would ask this of him. 2
Maharal #2 (Derush L'Shabbos Ha'Gadol, Hagadah Shel Pesach (end), p. 211): Someone's name is how others refer and relate to him. Moshe was asking, Hashem's providence and involvement is not evident in the course of nature; rather, it is hidden. (How, then, should the lesson of Hashem's relating to us be taught to the people?) 3
