Something that cannot be ignored, but seems quite glossed over in this thread of 400 comments: elementary and middle school are typically the best and most important day-care service for working parents. Especially anyone who is blue-collar and does not choose their schedule, any single parent who cannot be home at all during the day, double-income parents who are likewise absent.
It is one thing for comparatively comfortable white-collar homemaker moms to lovingly pack a little lunch for all their kids the night before. It's another thing entirely for them to send their kids packing and rely on the school itself to provide that nutrition.
And personally I see this as a bit of a dilemma. Because parenting and homemaking skills are often honed by the practice of preparing lunches and providing for the children. If you, as a parent, are not accustomed to doing this, you're going to bond less with those children, you're going to rely on state assistance more, and your children are going to bond less with you, resulting in a more distant relationship than one forged through the common experience of acquiring, preparing, and consuming food.
So free school lunch assistance is, in some ways, mandatory for a culture of working parents, and certainly if we're going to keep children out of the industrialized workforce, we need to keep them in school and well-fed. But at some point, children become quite dependent on the state and they are going to look to the state to provide other needs, as well, if the parents are not stepping up to that. So will children grow into full-fledged contributors who pull their own weight, or will they simply exist to expand the welfare state?