A friend who has been teaching about "euvoluntary exchange" got this from a student.
When he first explained the concept of BATNA and the situations in which BATNA is too low, I was all for changing those situations. However, we need to remember that if we're going to take away somebody's best option (even if it is a crappy one) then we're also going to have to give them a better alternative.
That is as good a concise summary as I could possibly imagine. Telling a poor guy in India who needs medicine for his daughter that he cannot sell his kidney is a rotten thing to do, unless you can also help him somehow. If you aren't going to help, give him access to the market!
And, we can't help everyone. But the market can.