Perhaps their goal is to increase applications to increase competition which, in theory, will increase quality. Perhaps following these statistics over the long run have shown that this works.
This. It doesn't matter if the couple of thousand new applicants are high-quality or low-quality. Even if they are horrible quality, rejecting them decreases our acceptance rate and increases are ranking in U.S. News and other publications. That's how the State University of Ohio- Columbus does it.