Why reject technology?
Advancement in technology raises closely both the ability to control society and the ability to create degeneracy.
To address the former you have to decentralize technology, giving the power of its use to the people. The downside is that the latter still applies, and the more decentralized technology is the more difficult it would be to control its results.
To address the problems with the latter you have to centralize it- the central authority will control technology and the greater control the smaller chance for people to create degeneracy. However, the former still applies and the greater centralization of technology the greater tyranny will be imposed upon people.
Apart from the obvious reasons any sane person, that is to say anyone thinking from a pre-absolutist mindset, or any other person who values freedom would object to total centralization, The chances a completely centralized authority would be a strong arbiter of morality are as slim as they are of it not being tyrannical. As can be seen historically, the greater centralized power is the more immoral it becomes. Less obligations to govern well naturally create less probability of doing so, including a much smaller emphasis on the morals their former power was built on: keeping a healthy nation, at the risk of deposal. As control becomes stronger and the chances of losing it become slimmer, the sole goal of those in power becomes staying in power.
You can easily say that decentralization of technology will solve the problems of an immoral oligarchy: but leisure, not power is the root of immorality in the masses. While an oligarchy has the slim chance of being composed of the "enlightened minority", there will never be an "enlightened majority".
The vast majority of humans do not care about much more than fulfilling their needs, and never have. When presented with the opportunity for leisure, few will turn it down. As can be seen, again, historically, the only successful means of controlling what would otherwise be hedonism or excess in society lies in force. Either a tyrannical, usually inefficient force, or by circumstance - as it was before the industrial revolution.
More so than any doctrine or innate characteristics, man responds to his circumstances. Man is an animal built to survive, and his instinct is to do what is necessary to survive, and especially, to thrive. It is unrealistic to expect the common man to impose challenges upon himself - virtually the difference between a leader and his followers, and as utopian as the horizontal society envisioned by Marxists.