" If we all spent more time on projects like this instead of the next 
   Twitter, or designing new weapons the world would arguably end
   up a better place."

This is an all too common attitude and one I used to share before spending time in the developing world. The plain fact though is that it is wrong.

Doing something is not always better than doing nothing. As a matter of fact a great many things, perhaps even most, interventions do more harm than good.

I'd recommend starting off reading "White Man's Burden" if you are interested in the topic. For a more fun example, google "one million t-shirts for africa"