Do we need such rapid improvements in technology? A new model for cars every couple of years, a new model for cell phones, a new model for a television set, a new model for a computer?
The improvements are surely not made with consumer in mind as PRIORITY. They are made so that people keep on buying "the new thing". Profits is what it is all about.
John Stuart Mill believed when living conditions get really good, working people will value them and through education will limit the number of children they can have.
This lack of people would cause the wages to rise and capitalists would not be as interested in investing into new technology and socialism will emerge with working people controlling more of profits.
OF COURSE, this system becomes useless with illegal immigrants and outsourcing in our times as more people that can do the work cheaper can be found outside of America.
What John Stuart Mill was saying is that, the life is already good and rapid changes in technology can be substituted for more energy to be spent towards human rights, social welfare and public service.