The parsha of havaas bikurim begins with "arami oved avi"- pesukim that a farmer recites when bringing his bikurim to the Beis Hamikdash. These pseukim describe our exile in Mitzrayim and our subsequent deliverance and entry into Eretz Yisroel. They are familiar to all of us as they are the same pesukim we recite on Pesach night as we fulfill the mitzvah of retelling the story of yetsias Mitzrayim. Why did Chazal structure the Hagadah around the text of the parsha associated with bikurim? Wouldn't it have been more appropriate to focus on the pesukim of sefer Shemos in which the original story of yetsias Mitzrayim is recorded?
Before the farmer begins the actual story he is about to relate, he presents the bikurim to the kohein and recites "higadeti hayom laHashem Elokecha ki bassi el haaretz - I have declared today to Hashem that I have arrived in the land." There are two problems with this declaration. The statement is said in the past tense, yet the farmer has not yet said anything. It would have been more correct to make this statement after he has concluded the story of yetsias Mitzrayim which culminates with entering Eretz Yisroel. Besides the placement of this statement at the seemingly incorrect place, the statement itself is difficult. How can the farmer who was born in Eretz Yisroel and is bringing the bikurim many generations after his ancestors arrived in Eretz Yisroel declare "ki bassi el haaretz - I have arrived in the land"?
In trying to understand these difficulties, we can think about the two ways that a story may be told. One can tell it in the third person, as a detached narrator, or, one can relate it in the first person as an active participant. We are commanded to tell the story of Eretz Yisroel and the subsequent entering into Eretz Yisroel every year when we bring bikurim. The Torah wants this story to be told as a personal one, not merely relating events that occurred to others. "Arami oved avi" is written specifically in the first person.
In addition, a story can be told with words alone, but a more effective presentation is achieved by dramatizing the actual events. Actions can express a message that words sometimes cannot. The Kli Yakar explains that when the farmer declares in the past tense "higadeti hayom - I have already told my story", he is not referring to the words of "arami oved avi"- but rather to the story told through his actions. The act of separating the first fruit, placing the fruit in a basket and coming to the Beis Hamikdash with basket in hand is itself a powerful story. Through this dramatization, the farmer has already declared, albeit without words, that Hashem has brought him to the land and he is expressing his gratitude for his harvest by presenting his first fruit to the kohein. The farmer now embellishes upon this "story" by reciting "arami oved avi".
The Torah requires that the introduction to the narrative of yetsias Mitzrayim emphasize "ki bassi el haaretz - I have arrived in Eretz Yisroel." Each time we bring bikurim we are commanded to do so as if it is our first year in Eretz Yisroel. The actual dramatization of placing the bikurim by the mizbeach and speaking in the first person of recent arrival in Eretz Yisroel places the story of "arami oved avi" in the proper context. It is a personal recounting of a Jewish history culminating with entering Eretz Yisroel.
There is another occasion when we are required to tell a story. The mitzvah of telling the story of yetsias Mitzrayim on the night of Pesach is also derived from the word lhagid - "vhigadeta lbincha" - a phrase similar to "higadeti hayom" of bikurim.
On Pesach we are also required to tell our story in a personal manner. The Rambam in Hilchos Chametz Umatzah teaches us that the actions of drinking four cups and leaning are fulfillments of our obligations to relate the events of yetsias Mitzrayim. We tell the story of our deliverance from slavery to freedom through our words and through our actions. On Pesach night there is an obligation to view oneself as leaving Mitzrayim at that moment. The Rambam formulates this requirement as "bechol dor vador chayav adam liros es atzmo kilu yatzah ata miMitzrayim - in every generation one is required to view oneself as if he is leaving Mitzrayim right now." It is not sufficient to even view yetsias Mitzrayim as a personal event of one's past. One has to internalize it as an event of the present. The physical dramatization of the seder and the obligation of "bechol dor vador" put the seder night in its proper context.
What more appropriate a text to use for the seder than the parsha of bikurim. "Arami oved avi" is the personal story of Jewish history. Yetsias Mitzrayim as recounted in sefer Shemos in the third person would place the events that occured to others in the distant past. "Arami oved avi" told in the context of drinking four cups and leaning is the personal story of yetsias Mitzrayim told both by word and action.