"The vast majority of workers in poor countries are agriculture workers"<p>I think that's not true, and population trends are strongly against it, largely because of improved sanitation.<p>For example, Nigeria is the most populous country in Africa, urban population is about 50%.  I'd bet their urban population is growing like crazy while the rural is shrinking.<p>"Job opportunities are important, but lowering mortality rates helps this."<p>Not always.  That's a big assumption.  Are there massive job opportunities around that require cheap labor?  There are in China.  They are getting to be rich by manufacturing.  Not because Americans came in and solved all their health problems.  Because Americans opened their markets and there was a government in place that enable the country to take advantage of that (a dictatorship with a bunch of problems, no doubt, but you can't say they haven't fueled economic growth).<p>"People dying young is inefficient, since it makes education and training more expensive"<p>Unskilled labor is by definition not educated or trained.<p>"eliminating Smallpox has made the world a worse place"<p>Well, it's highly subjective to say what makes a place better or worse.  What are we trying to maximize?  Human-life-years lived? Or human-life-years-lived without living under dictatorships, constant war and corruption?<p>Sure, research in medicine always has value.  But making existing vaccines 10x cheaper the best alternative right now for our society to spend it's excess wealth in?  Why does any of this matter if sea levels go up a few feet, and tens/hundreds of millions are forced to flee over national borders (and that leads to massive conflict)?