Wouldn't it be a better if all admits are informed asap, then allocate financial awards to those who accept offers...
"The SIPA Admissions Committee actually spends twice the amount of fellowship money we have. Why do we do this? Because history shows that not everyone we award funding to will attend. Thus we greatly overspend which means that if an applicant declines their award, we cannot simply shift that money to another applicant." (Sipa Blog, March 15, 2010)