I saw that. I do not have any inside information on this subject, but in the video, the Adcom states that they went to this policy because visiting and interviewing was a burden on some students and it created an uneven playing field putting people with less money (or greater travel distance I guess) at a disadvantage. She also specifically mentioned international students and said that the old policy made international students that were not able to visit campus feel that there were at a disadvantage in the application process.
I think the other obvious factor is that Darden's applications were up 35% last year - I believe they said in an earlier podcast that this was the largest increase among top schools and came on top of double digit increase for the 2 prior years. Obviously it takes a lot of effort and manpower to interview all those people so perhaps they felt stretched.
Finally, I'll speculate that they probably concluded they were wasting a lot of resources interviewing people that didn't end up submitting applications. The old policy was that they would interview everyone, even those that hadn't yet turned in applications, and I believe even those who hadn't yet paid an application fee. This was broader than even Kellogg & Duke, which interview virtually all applicants, but only after they turn in their applications and pay the fee. By interviewing these people prior to collecting a fee or application, I think that they lost out on some application volume because people who had poor interviews would just forgo applying.
I don't believe the fee was an important issue, but application volume is a huge concern (for all schools). If they collect a bunch of applications from people who then drop out after interviewing, they can still count these people in their application statistics - impacting both admit rate and yield. On the other hand, under the old system, people who would have otherwise turned in applications probably dropped out after poor interviews, negatively impacting application volume and yield.
They did say in the interview that they intend to meet with a lot of applicants, and I believe they will stick to the completely blind interview process - which is the most open exchange that I encountered with any school throughout the process. In fact, I believe she states in the interview that most applicants will still have a chance to demonstrate their character in an interview. I believe the new system is in place to reduce the burden on people early in the process, and encourage more people to turn in applications.
Darden is also reducing the number of essays from 4 to 3. I believe both policies are in place to encourage higher application volumes to improve selectivity and yield numbers. I think that applicants will still have a chance to prove themselves in interviews.