The problem is that human social mores seem to change on the order of 20-40 years which is consistent with the amount of time it takes a new generation of people to take the helm and for the old generation to die out. I have personally seen extreme societal change within my own country of origin, change that happened in only the span of 30 years. In comparison, Western culture over this same time has seemed almost stagnant (despite the fact that it, too, has undergone massive changes such as acceptance of homosexuality).

However, by some estimates, we are already just 20-40 years away from the singularity (2035-2055). This seems like too short a time for human culture to adapt to the massive level that is required. For instance, consider a simple thing like food. Right now, the idea of eating meat that has been grown in a lab seems unsettling and strange to many people. Now consider what future technology will enable, step-by-step:

• Food produced by nanotech with simple feedstock, with no slow and laborious cell growth required.
• Food produced by nanotech with household waste, including urine and feces (possibly the feces of other people as well), thus creating a self-contained system.
• Changing human biochemistry so that waste is simply recycled inside our bodies, requiring no food at all, and just an energy source plus some occasional supplements.
• Uploading brains. Food becomes an archaic concept.

There is likely to not be a very large span of time between each of these steps.