I once heard a Shabbat Haggadol D'rashah by a Lamdan in which he posed the following Query: "Why did Hazal choose to Darshen Arami Oveid Avi for the Seder? Why didn't they choose other p'sukkim of G'ulah?"
Note: Many years earlier I had been bothered by another question. The Tosefta says that those who could not say Hallel by themselves gathered in Shuls so that they could hear it being led by the Sha"tz, etc. My question was, "If one could conduct a seder alone, couldn't he handle Hallel, too?"
The answer to the first question answered my question, too. That is viduy bikkurim was well known to the amei ho'oretz who recited it annually in the Beit Hamikdash. And so Hazal selected that in order to make it easy for the amei ho'oretz because these p'sukkim were already well- known.
And since these p'sukkim were well- known, the were probably also more familiar than Hallel, too. Which explains how an am ho'oretz could conduct a seder and stilll not lead Hallel.
Mussar: Hafach Bah.... Sometimes learning Y helps us to better understand X. An answer to another question, served to answer my question, too.