On one hand I agree: yes things like this are a step into what is common tech for us in the hands of people all over the world. On the other hand I sometimes have serious doubts about whether it is really needed to push our consumption society into these countries where there are often still problems with basics like clean water/hygiene/electricity/birth control/housing/western influenced dirty industries/...
Oh don't get me wrong, I don't look at cheap computing as trying to push a 'consumption society' of watching Netflix in a village in India. I referred to the Khan Academy (lite, low bandwidth version) for example. I look at these things really as a way to emancipate and empower. I can't imagine where I'd be without the internet, how many things I have taught myself over the years, questions I have been able to answer I wouldn't know who to ask, or even dare to ask if I did. And currently I'm relearning my highschool math and beyond for free, after a decade of never touching calculus in real life and forgetting everything about it. If I'd have to choose between giving up things like google or hell, HN vs Netflix/FB/Amazon, I'd give up the latter in a heartbeat. And that's really the hope I have for cheap ubiquitous access to computing. I see these devices within the spectrum of education and empowerment first and foremost, things that can help solve the issues you mentioned.
Anyway I fully agree with you, there are other priorities. Clean water, electricity, birth control etc. But that's so exciting about cheap tech. At $50 over 3 years of lifetime, you're paying 4 cents a day, for a device that looks to have slightly better specs than the $500 iPad 2 of just 4 years ago. Imagine where the price goes in a few more years, to 2 or 3 cents? And then consider you may share it with one other person, or multiple in a classroom, and buy it secondhand or in bulk (e.g. the fire tablet itself costs just ~$41 rather than $50 if you buy 6 of them at once.) We might be looking at a cost of computing of 1-2 cents a day, that's not insignificant if you earn $1 or $2 a day, but it's getting so cheap that it's no longer a big tradeoff between this and say electricity. Soon you can meaningfully have both.