There is a lot written to try to explain Rashi's comment on וָאֵרָ֗א אֶל־אַבְרָהָ֛ם אֶל־יִצְחָ֥ק וְאֶֽל־יַעֲקֹ֖ב that וארא אל האבות. We know Avraham, Yitzchak, and Yaakov are the avos. Why is that relevant to pshat in this pasuk?
My son dealt with this question last week on his blog and quoted, among other ideas, the L Rebbe who explained that Rashi is highlighting the fact that Hashem appeared to Avraham not only because he embodied the midah of chessed, and to Yitzchak not only because he personified gevurah, and to Yaakov not just because he was an exemplar of tiferes. Hashem appeared to them because they were avos, they were the forefathers of our nation, they passed those midos down to future generations. אבות מכלל דאיכא תולדות (Bava Kama 2) R' Meir Goldvicht in his shiurim always likes to say that maaseh avos siman la'banim means the maaseh avos are part of our genes, our spiritual DNA. Hashem was telling Moshe that it was not time to deal with abstract questions about why the galus was so difficult. He had to try to connect with the people in a more direct way, in a more emotional way, so that they would be receptive to his message.
It's interesting that the Sefas Emes (last piece in 5637) goes in nearly the opposite direction. Rashi later in the parsha (pasuk 9) quotes from Chazal that these opening pesukim are a response to Moshe's question of why Bnei Yisrael had to suffer:
ורבותינו דרשוה לעניין של מעלה, שאמר: למה הרעתה וגו׳ (שמות ה׳:כ״ב). אמר לו הקב״ה: חבל על דאבדין ולא משתכחין. יש לי להתאונן על מיתת האבות, הרבה פעמים נגליתי עליהם בקל שדי, ולא אמרו לי: מה שמך, ואתה אמרת: מה שמו מה אומר אליהם
Simple pshat is that Moshe is being told that he is not on par with the avos. Sefas Emes, however, interprets the point as speaking about Bnei Yisrael, that theywere not connected to the avos. חבל על דאבדין ולא משתכחין -- the avos are gone and cannot be found because Bnei Yisrael failed to carry on their legacy and live up to it. The spiritual DNA may be there, but it is not expressing itself. Therefore, the galus is a harsh one.