Because the NCAA wants to encourage schools giving scholarships to amputees (hence the .7)? :dunno
Seriously, I think it's because Baseball isn't a revenue neutral or revenue generating sport for most schools (unlike DoNU). That, and Title IX complications that prevent schools from offering scholarships for all baseball players, I'd wager.
Football, Men's & Women's Basketball, Women's Volleyball, Women's Gymnastics, and Women's Tennis are all "head count" sports, which means any scholarship is a full scholarship. All the other sports are scholarship equivalency sports, so partial scholarships are awarded.
I just don't understand the reasoning, I'm sure there is one, because it's the NCAA... :sarcasm
Seriously, I think it's because Baseball isn't a revenue neutral or revenue generating sport for most schools (unlike DoNU). That, and Title IX complications that prevent schools from offering scholarships for all baseball players, I'd wager.