I suspect it's because there're lots of people who would like to do fine arts, so they make all of the 100-levels incredibly intense to filter in just the ones who are really talented and dedicated. Sometimes I wish they'd do the same thing with the CS department.
This used to be somewhat traditional, to have a hardcore 100-level CS class as a weed-out, but my impression is that curricula are moving away from it. Partly, there's a worry that it mainly rewards how much knowledge you have coming into college: if the CS-101 course is really hardcore, the people who pass it are those who learned a lot about computer science on their own in high school. But if the university is supposed to provide an education program that can teach CS to people who don't already know it, that isn't quite what you want.
It also tends to work directly against universities' recruiting goals: they're spending all this effort to try to convince "non-traditional" CS majors (i.e. people who weren't already high-school computer enthusiasts) that it's an interesting and useful field to study, in which case you don't want to immediately kick them out in the first semester for not already being proficient enough.
This used to be somewhat traditional, to have a hardcore 100-level CS class as a weed-out, but my impression is that curricula are moving away from it. Partly, there's a worry that it mainly rewards how much knowledge you have coming into college: if the CS-101 course is really hardcore, the people who pass it are those who learned a lot about computer science on their own in high school. But if the university is supposed to provide an education program that can teach CS to people who don't already know it, that isn't quite what you want.
It also tends to work directly against universities' recruiting goals: they're spending all this effort to try to convince "non-traditional" CS majors (i.e. people who weren't already high-school computer enthusiasts) that it's an interesting and useful field to study, in which case you don't want to immediately kick them out in the first semester for not already being proficient enough.