This is very interesting. I haven't read the book, but I think the comments about a lack of 'unstructured' time are dead-on. I remember being able to disappear into the woods behind my house for pretty much an entire day, unsupervised. My summer vacations used to be 3.5 months or so; today, where my mom teaches it's just barely more than 2 months. They're being robbed!
There's also just a current cultural phenomenon that today's parents seem much more involved in their children's day-to-day lives, even the older kids [judging from my work in college student affairs]. Maybe a way the UL/LW philosophy can make an indirect impact is through the parents, reviving the interest the old folks used to have, but this time lighter and easier on the body. Not to mention logistically easier--fewer items to sort and carry, shelters you can pitch in 2 minutes, stoves that start cooking as soon as you flick the bic, packs whose straps you can understand at first glance... Your campsite need not cover an acre.
Another thing I was musing on earlier today is young female interest in outdoor activities. I wonder what the numbers and trends are like for hiking, climbing, mountain biking, etc. One way UL/LW can help is simply 'de-macho-fying' the backpacking image. The 'tough guy' notion of carrying 'monster loads' seems to be fading a bit, and that's a good thing. Time to wake up and realize that hiking does not mean sweat and suffering, and you don't have to be an athlete. It can be pretty easy.
Hmm...what else... I think the rise of adventure racing is a good thing, a uniquely outdoor activity that has its own edgy mass appeal, and could probably attract the younger crowds better. Maybe social hiking just lacks that competitive edge? [which is just fine by me] The thru-hiking community also seems like one that's improving on the awareness it's always had. Ceterus paribus, a lightly-loaded hiker probably has a better finishing chance than a heavy-load. The more reasonably burdened the rookies start, the more likely they'll be to meet their goals and continue to enjoy the experience. Those who complete the hikes probably come away with a different perspective on nature.
The main education channels may need to change a bit as well, though I don't know how enthusiastic that will be. NOLS, Outward Bound, BSA, could all make some progress in outdoor gear philosophy. Less paranoia, more self-reliance [less off-the-shelf-reliance]. I know legal CYOA policies need to be kept, but there is room for improvement. As for the media and other more informal education outlets, BPL sets a fine example that the larger print mags would do well to follow. I think one of the best parts of the UL/LW mindset is the underlying approach: asking what works, what doesn't, why. A mission to understand the technologies, driven by a need for function, simplicity, reliability, ease of use, minimal impact on earth and body.
Hopefully I hit some talking points, looking forward to other responses.