The mitzvot related to חִפָּזוֹן were only for the pesach of Mitzrayim. Ralbag posits that matza and marror were also done because of חִפָּזוֹן, if so then why would matza and marror remain for all generation and the other mitzvot fall away if they are all done because of חִפָּזוֹן? In truth all the mitzvot of korban pesach that were done in Mitzrayim were done for different reasons then the mitzvot of the post-Har Sinai korban pesach. This is because the purpose of pesach mitzrayim is different from the purpose of pesach l'dorot.
Four things must now be clarified: A) What was the purpose of pesach mitzrayim? B) Why did pesach mitzrayim require חִפָּזוֹן? C) What was the purpose of pesach l'dorot? D) Why is pesach l'dorot eaten with matza and marror?
The entire procedure of the korban pesach in Mitzrayim, culminating with its consumption, was to demonstrate the rejection of Mitzri idolatry. In order to demonstrate their absolute conviction that Hashem would immediately redeem them they ate it with חִפָּזוֹן. The חִפָּזוֹן itself was a blow to the false power structure of Pharoe. One would think that even if Pharoe were defeated it would still be necessary to go through the slow diplomatic process of arranging the release of the Hebrew slaves - nothing can happen overnight in politics; certainly some negotiations would have to occur. The geula from Mitzrayim was different - it did not occur through any know causal structure - it did not occur by playing to a pompous bureaucracy. This is the meaning of "lo al y'dei malach" - not through any know causal system - it was HaKadosh Bar'chu:
וַיּוֹצִיאֵנוּ ה מִמִּצְרַיִם--לֹא עַל יְדֵי מַלְאָךְ, לֹא עַל יְדֵי שָׂרָף, לֹא עַל יְדֵי שָׁלִיחַ, אֵלָא הַקָּדוֹשׁ בָּרוּךְ הוּא בִּכְבוֹדוֹ: כְּמוֹ שֶׁנֶּאֱמָר "וְעָבַרְתִּי בְאֶרֶץ מִצְרַיִם, בַּלַּיְלָה הַזֶּה, וְהִכֵּיתִי כָל בְּכוֹר בְּאֶרֶץ מִצְרַיִם, מֵאָדָם וְעַד בְּהֵמָה; וּבְכָל אֱלֹהֵי מִצְרַיִם אֶעֱשֶׂה שְׁפָטִים, אֲנִי ה" שמות יב,יבThe entire power structure of Mitzrayim was reduced to rubble. The immediacy of their exodus further demonstrated this breakdown. B'nei Yisrael demonstrated their absolute trust in Hashem - that he would take them out of Mitzrayim immediately as a direct result of eating the korban pesach.
Yitziat mitzrayim was the ultimate demonstration of Hashem's absolute dominion and the utter fantasy of human power. The enslavement made absolutely clear where the fantasy of human power must lead - tyranny and oppression. Tyranny can only occur when man believes that all is happenstance - keri - and matter for man's dominion. Before Sinai B'nei Yisrael had rejected the power of Mitzrayim but could not fully accept the yoke of heaven until Har Sinai.
What was the new significane of the korban pesach post-Sinai? Rabban Gamliel says:
פֶּסַח שֶׁהָיוּ אֲבוֹתֵינוּ אוֹכְלִין בִּזְמָן שֶׁבֵּית הַמִּקְדָּשׁ קַיָּם, עַל שֵׁם מָה--עַל שֵׁם שֶׁפָּסַח הַמָּקוֹם עַל בָּתֵּי אֲבוֹתֵינוּ בְּמִצְרַיִם, שֶׁנֶּאֱמָר "וַאֲמַרְתֶּם זֶבַח פֶּסַח הוּא לַה, אֲשֶׁר פָּסַח עַל בָּתֵּי בְנֵי יִשְׂרָאֵל בְּמִצְרַיִם, בְּנָגְפּוֹ אֶת מִצְרַיִם, וְאֶת בָּתֵּינוּ הִצִּיל; וַיִּקֹּד הָעָם, וַיִּשְׁתַּחֲווּ" שמות יב,כז.We must focus on how our households were saved in Mitzrayim and we were not afflicted with the plague of the first born. We no longer eat the pesach to reject the Mitzri idolatry - it becomes an instrumentality of our ever deepening recognition of and gratitude for Hashem's hashgacha. In this framework matza and marror must take on a new significance. Before Sinai B'nei Yisrael had rejected the power of Mitzrayim but could not fully accept the yoke of heaven until Har Sinai. The post Sinai matza is the bread of subserviance to Hashem's dominion. The eved Hashem is not preocuppied with the form of his bread - he is not interested in its pleasure producing characteristics. As one reflects on Hashem's hashgacha while eating the pesach the bread of subservience to Hashem's design is eaten. The purpose of the marror requires further thought.