This is a really interesting dilemma to consider. I wasn’t really aware of the AP Physics 1/2 controversy until recently.
Some background: I graduated high school in 2011. I took AP Physics B my junior year of high school. I self-studied for both AP Physics C exams my senior year. My high school did not offer AP Physics C, but I wanted to pursue an engineering major in college and place out of freshman-level physics. My views here are those of a relatively uninformed outsider.
AP Physics B already offered too much material to be taught in one semester. I believe that the exam required knowledge of classical mechanics, E&M, thermodynamics, fluid mechanics, sound, optics, and nuclear physics. This corresponds to three semesters of algebra-based physics in college, compressed into eight months of a high school class, give or take a couple of weeks depending on school start date. The class itself was insane, and we had to self-teach nuclear because we simply did not have time to cover it in school.
The issue with AP Physics B is that the credit is generally useless for anything but majors with a science elective requirement. Engineering majors cannot use it because it is not calculus-based, and pre-med students cannot use it because most med schools, from what I understand, do not accept AP credit for the science and math requirements. Even if you had planned on using the Physics B credit as science elective credit, I would assume that more students would take AP Biology or AP Chemistry for that purpose. (More than twice as many students took bio than physics B in 2014, and 50% more took chem than physics B.)
The question is, then, how many high school students want to commit two years of high school coursework on AP Physics 1 and 2, exams that will do little to no good for them in college? As other posters have implied, it seems like a lot of schools are going to see heavily reduced enrollment in AP Physics 2 because 1. schools are pressuring students that are not ready for AP Physics to take the class, who then lose faith in their STEM abilities, and 2. students may want to take a different science course—bio, chem, or environmental science.
I obviously do not have the expertise of the College Board, but I just can’t understand why they thought that turning AP Physics B into a two-year course would be a good idea. I would have proposed that they remove material from the death march that is AP Physics B in some sort of a curriculum overhaul, but keep it as a one-semester course.