I also agree that CBS is waiting for the 3/4 (TODAY!) deadline for accepted students to gauge where it stands before admitting more students. CBS has a new admissions Dean and I assume she is changing things to improve the yield of accepted students. CBS has a yield of 72% compared to the 89% at Harvard. I assume the new Dean wants to increase the CBS yield into the high 70%'s. Yield is important for school rankings and has always been an issue for CBS with top candidates opting for H/W/S instead.
Lets say you had an Interview invite from H/W/S but got accepted from CBS early in the game and had the 03/04 deadline, some students may opt to pay the 1500 and enroll than take the risk over other schools which usually confirm acceptance later.
Good for CBS for flanking H/W/S, say hello to H/W/S/C!