As I said, it may not be intentional but rather a side effect of too many applicants who want to major in one specific field sounding too similar that the personal rating ends up being penalized. A student who is studying the Classics and shows a high level of interest in this area is going to stand out far more from the applicant pool vs another student interested in medicine, for instance.
The CS boost in admissions is odd and seems like a real outlier, especially as you would think the Personal Score which was the lowest would have had more of a negative effect in the admissions process but it is possible that the school suddenly expanded the CS program due to increased interest in CS thus boosting admissions with increased number of seats. I wonder if these values change over the 10 year period.
By the way, the list for Personal Rating may actually follow this trend. There are quite a few students who wish to major in biology (often pre-med) and engineering, for instance. It would be interesting to know how many applicants with a given intended major there are compared to how many students graduate from that major. While CS would be nowhere near as common back then, it is very likely even then there were far more CS applicants than students declaring an interest in Russian literature, for instance. There are also far more spaces for CS so the question is what is that ratio of applicant to slots for the intended majors? I know technically at these schools there are no “slots” but there are only so many faculty and only so many students they can allow into a class. Plus, they need some students to enroll in those Classics classes etc.