Any child that goes through the education system will have a better chance of being a successful contributor to society. Also, schools will teach content that people, citizens of the U.S. should know. What our children learn in schools today is seen as useless and ethnocentric. It's role as equalizer is oftentimes overshadowed by its role as baby-sitter in a society that now puts both parents to work. I think the answers lie in Marxist theory.
Writing is a social activity.
Even cognitivists can not ignore that language is a social construction, so whatever way words go on paper, its beginnings are ultimately social. A writing teacher's role should be to re-introduce students to why they write and who they write for. It should be taught as a social act in which the writer must interact with others before the first draft, during revisions, and throughout all subsequent drafts. Rather than making writing a competitive act, the writing process should be nurtured. Writing improves for a person when they focus on a specific genre, a community that judges good writing in very specific ways.