Children are amazing at coming up with creative ideas and solutions. It is also amazing to see how they reject or adopt an idea as well as the ways in which they try out ideas.
Furthermore, the education system worldwide and particularly in the US and Asia needs a complete overhaul. What better way then to engage children to solve problems of importance to the society around them (local or global)
Also many of the problems you list have a deep impact on children and so it will be children helping children - remember "We are all in this together and I am pulling for you"
See Beau Lotto's TED talk for reference (https://www.ted.com/talks/beau_lotto_amy_o_toole_science_is_for_everyone_kids_included?language=en)