I think you're evading babyrainbow's question. Many new technologies have been developed, true. But we've also spent the last century conducting experiments in communism and genocide. So on the whole, are we (and I'm including the whole human race in "we") better off in all respects or only in some?
You don't think genocide happened before ww2? Genocide is very old
Look at the Old Testament for descriptions of too many genocides.
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If graded on a curve, the 20th century comes out as a pretty nonviolent genocide-free century.