No they don´t make you withdraw from waitlists, unless they changed something this year. The new system is not a matter of "dumb", so much as "you are not their top priority". The story I´ve heard is that medical school is switching from a traditional cirriculum (histo and anatomy as seperate courses in the fall) to an integrated systems cirriculum (Anatomy remains a separate course, I think, but histo is now part of some cell/histo/fundamentals of medicine supercourse, again I think, I haven´t actually gotten a schedule yet).
I´m pretty sure the story is that they haven´t figured out how to alter the ACP program yet, so they´re just having you all take Histo in the Summer, and evaluating you on the same Histo/Anatomy combination they´ve always used. Eventually I´d bet they change the program to reflect the new cirriculum, but not this year. If that means that 3-4 kids get in off waitlists and next year´s class has to make do with only 12 Anatomy TAs, in addition to their half a dozen Anatomy professors, I think the school will find a way to live with that. Especially since most medical schools get by with one or two professors, half a dozen non-medical student TAs, and a shorter Anatomy course.