> Spreading the work around increases the wealth of the human race as a whole
This is true, the economics are pretty straightforward. And it is working very well for the 2nd and somewhat 3rd world. the problem is the disproportionate wealth accumulated in teh first world will 'leak' into the wider pool. Eventually, that pool may rise enough to bring everybody to the standards of the 1st world, but, imho, not for a long time, if ever. This isn't such a good deal for the people in the 1st world who will lose access to the standard of living that they have been enjoying.
To think of it another way, this is similar to having the 1% spread their wealth to everybody in America. Or even just the poorest half. that would, likely, jumpstart the economy , people invest in education and more people have the chance to innovate. In aggregate, everybody is wealthier. But the 1%s will be poorer and won't attain the same levels of wealth accumulation in the foreseeable future.
It is hard to sell people on such an altruistic ideal at their own expense. It is likely what will happen (worldwide, not the 1% analogy) but, imho, standard of life in the first world is going to drop considerably.