Many have said that the Pew study reflects a catechetical failure. I fear the opposite: it reflects a certain kind of catechetical success. It is the result of an unwritten catechesis that American Catholics have been slowly learning. Through a deracinated, spiritualistic, and emotivistic treatment of the Eucharist, many Catholics have learned their faith from a generation of pastors who stripped the altars, razed the bastions of reverence around the Lord in the sacrament, and who generally treated the Most Holy Eucharist itself as something to be passed out like a leaflet rather than received in awe, as people prostrate before the fire of divinity. Far too many have received this kind of unwritten catechesis.
Chad Pecknold writes much more here.