GDP is a weak proxy for wealth. We are much more interested in adding up the consumer surplus and the producer surplus, but getting accurate numbers is usually impossible.
If we are comparing economies that are, in a suitable sense, "the same shape" then more GDP is better. But adopting new technologies in the way that your question imagines, changes the shape in a way that breaks the proxy. GDP goes down and that is a good thing. No surprises or paradoxes here; GDP is well known to be a poor proxy for wealth.
If we are comparing economies that are, in a suitable sense, "the same shape" then more GDP is better. But adopting new technologies in the way that your question imagines, changes the shape in a way that breaks the proxy. GDP goes down and that is a good thing. No surprises or paradoxes here; GDP is well known to be a poor proxy for wealth.
http://lesswrong.com/lw/jmm/true_numbers_and_fake_numbers/ai... works through the details, but the other way round - the robot breaks down, prices go up, GDP goes up and that is a bad thing.