I haven't read Kurzweil but the idea is very inventive and alluring however I tend to agree with you. My reasons might be different from yours...
I think these futurists are full of shit. They discuss technologies as if they are to save mankind in some way or another.
It all goes on the assumption that we can keep our civilization running, yet we enter into an era of peak resources, climate change and the subsequent disorganization that will disable much of current R%D.
These people are not grounded very well. They are high priests of technology with a belief system, not anything solid.
Our society cannot go on for much longer because of climate issues and resource scarcity and of lack of values and morals.
I cannot see our way of life endure much longer or even stretch into the far future. I think within the next 100 years we will see so much resource warfare, migrations of refugees, soil erosion, diminished yields in agriculture, pollution, aquifer issues, access to drinking water and so on and so forth that globalism will collapse, economies will suffer and come to a grinding halt, society will shrink to proportions of around 1850.
Imagine the last ice age, when in the Indus valley a blossoming civilization rose to greatness and that there were great floods that wiped out entire regions of the Earth suddenly and changed the climate. And so they dwindled.
We think our civilization lasts forever. But our way of life is unsustainable, and no matter what technology we throw at it, this technology will cause new problems. Technology is the problem and you cannot solve a problem by doing more of the same thing.
So these futurists are all in the grip of delusional thinking.
There is not going to be a technology that saves us from ourselves. Kurzweil and his nanobots... It amazes me how someone can dream up that shit while we have people dying because in the 50's and 60's they drilled, sawed and broke asbestos used in construction. And now he wants to infect people with nano-scale technologies, as if somehow that won't cause any harm. Futurists rarely look back, so they don't know what and why things went wrong and why the world is what it is today because they have their heads stuck up the ass of the future.
We need less technology and we need technology that helps all mankind. Not some type that mainly benefits the rich western lifestyle paradigm.
Who wants an Ipod when a poor bastard dies of some trivial disease in Bangladesh?