That was because we wanted them to live away from home & experience learning to get along with people who didn't have to love them. Once they got a taste of freedom, they kept living on their own but paid their own way. They also got 1/2 tuition if got admitted to BYU as a faculty kid.
Think your plan is very generous but you know what you can afford.
BTW: My parents didn't help more bc they couldn't spare more than $20 a semester.