Miss Universe are typically modelling, so large breasts would hurt their chances for print and runway work. Because, like Bill Maher had said, white women and gay men run the fashion/modelling world. And women tend to hate on those who are prettier, have bigger busts, butts, and are "sexier" than they are. Plus, it's about the fashion not the women.
Donald Trump owns the Miss Universe. So he is the one who could "change the judging standards"...but why.