[Eauz]

The use-value people want over time stays the same. We're tired, cold, hungry, lonely, bored, excited, confused, ambitious, etc.

Of course, but the means of changing this feeling always changes. For example, the way we warmed up is different from the 1800's and today. The way boredom is changed is different from 1900's and today.

You cannot socially engineer desire itself. You can only engineer how desire is satisfied, and even the satisfaction of desire has fixed emotions.

This is exactly what happens throughout history. The desires are satisfied, but they are satisfied through different means. Consumerism is only a recent occurrence in society. This is social engineering at its finest. Before that, there was a major change between the feudal consumer and the capitalist consumer. Desires and interests were engineered completely differently, due to the mode of production changing.

What is painful is painful. What is pleasurable is pleasurable.

Correct, but the pain of the 1500's occurs in a different manner than that of today. It is also cured through different means. The same holds true for pleasure. Social engineering has occurred throughout history, especially through the change of the mode of production. Culture also held a key aspect of the use-value of people.

[Daktoria]

I don't think you're getting it.

How do you find universally agreeable relations of production without genetic engineering?

For example, say you have to dig a ditch for irrigation.

Some people will feel the digging is more painful than others. Everyone will not feel the digging yields equitable pleasure.

What right do you have to expect everyone to participate? Even if different people do different roles, they will argue over who should have the least painful and most pleasurable positions.