Wow, I can't believe I made it through this entire thread and, although there's lots about shopping for and cooking food, there's nothing about producing it!
My perspective is that producing food has been an essential life skill for the vast majority of human history and that we are in a relatively brief bubble of industrial food production which may soon end, or at least end as we know it. My attitude is also at least partially regional, but here in rural Nova Scotia virtually all the families we associate with do some of their own food production through gardening, farming, hunting, fishing, etc. These are complex skills, too--many take years to learn to do well.
Mass-produced food is getting more and more expensive, even as paychecks get smaller, and many crop systems are susceptible to mass disaster (both oranges and bananas are on the brink of crashing already, for example). I sincerely hope I'm wrong that food production will become a vital life skill again within our children and grandchildren's lifetimes, but I sure wouldn't lay any bets. Therefore my 6 year old knows how to compost leftovers, mulch a raised bed, save seeds, use a cloche, cure a squash, etc etc.
I think those things are great skills to learn. However, some of us can't really make nay practical use of them. If I cleared every other bush out of my "garden" (which I can't do, without the permission of the landlords, anyway), I'd have a space about 4' X 12'....which floods whenever it rains, because of the way the land is sloped. One of my neighbours, who has a bigger space, which doesn't flood (we're in an end unit, and there are various issues with that, with respect to the garden plot) has most of her garden space devoted to veggie production in the summer. That creates a fraction of what her family of four needs, and even with a community garden plot (in short supply - I was on the waiting list for two years running), they don't produce even close to half what they eat....probably under a quarter, by her best estimates. I think those are all great skills, but a person needs access to land to make real use of most of them.