Just my two cents worth:
A lot of things have been “dumbed down” in the United States over the years.
I’m 65 years old. When I was in high school (a Catholic high school), we had four years of math, three years of science, and two languages (three years each). Everyone in the school got all that.
Seems to me that extensive math, science and language is no longer required; those who want those subjects can choose them, but they are optional or elective rather than mandatory. AND, to make matters worse, students often must decide in grammar school that they want to be in the “math track” or the science “track” when they are in high school. Once out of the “math track”, it is almost impossible to get back into the math track; they will be in the “dumb track”. There is also “emphasis” placed on making math as tedious and boring as possible.
Seems to me that there is also less emphasis on learning American history and world history than 50 years ago.
I would also say that the Catholic Church in the United States no longer teaches the Catholic religion.
In fact, one of the reasons for the existence of Catholic Answers is to attempt to fill the void. In my opinion, the average Catholic in the pew used to be very knowledgable about the tenets of Catholicism. (Not everyone back then and not in every aspect; but certainly the average person 50 years ago was more knowledgeable than today’s Catholics.)
However, and to make matters worse, the forces of something … “modernism”? … decreed that “rote memorization” was bad. So, use of the Baltimore Catechism (which was published in several different levels of comprehensiveness, for students at different grade levels) has been dropped because students were required to memorize the Q&A formatted topics.
In a discussion one day at work, one of the Hindu fellows displayed tremendous knowledge of Catholicism. When asked about it, he said that in India they studied all religions. One of the Catholic fellows then said, “Catholics learn their religion by osmosis.”
So, in summary, in my opinion, attendance at Mass is down because folks don’t know what the teachings of the Catholic Church are because they haven’t been taught by the Church. American Catholics have been put into the “dumb track”.
This will be the BIG scandal of the Catholic Church: that the hierarchy of the Church today has failed in its obligation to teach.