The use of remittitur and additur in American jurisprudence is based upon Justice Story's "very limits of the law" in conjunction with the constraints of the seventh amendment. This author states that since additur is not presently being used as a procedural devise and remittitur is premised on the same principles, the current use of remittitur should be eliminated.
Irene D. Johnson, Remittiturs (and Additurs) in the Federal Courts: An Evaluation with Suggested Alternatives, 38 Case W. Res. L. Rev. 157 (1988), available at http://digitalcommons.pace.edu/lawfaculty/531/.