This is one of those quick thoughts that usually gets me in trouble.
The debate about the innovation slowdown seems to be taking a very US centric view of the question. The people making the innovation slowdown argument are, in general, the very same people who laud what recent technology has done for the poor in many developing countries around the world. The invention of the modern kitchen didn't do much for them, but digital, transportation, and other technology has changed that. Some of them can now afford a kitchen, well of sorts anyway.
I am not fully convinced that we are as stagnant as people are saying, but in any case, just because innovation hasn't raised the standard of living in the US as fast as in the past doesn't mean that it hasn't had an impact around the world. If you were to compare the number of people lifted out of poverty by the invention of refrigerators versus those lifted out be recent technology that allows them to build those refrigerators for others, what would the answer be? Which innovation provided more value to the world? The growth may not have been here, some of it may have, in fact, moved away from here, but there was growth nonetheless, and growth that made a real difference to the lives of the poor around the world.
Anyway, just trying to provoke discussion.