Part of the goal for many students is to find a mate. That's hard if there are two girls for every guy, or the reverse.
Reaction: What if a college degree didn't seem so essential to young women who want even halfway-decent jobs? The article notes that men in HS-is-good-enough jobs are very often paid considerably more than women in such jobs.
One could argue that state schools should not do this. It should be noted that MIT and other tech schools boost women, and that there are a number of women's colleges that exclude men entirely.
Colleges with too high a ratio of females to males become less attractive to females.