Well, the basic problem with your premise is that socialism is based on violence and coercion and fosters a political class that maintains its hold on power by making people dependent on the state for their livelihoods while constantly fostering mutual antagonism such that people fear their neighbors more than the state.
Socialism requires a unequal concentration of political power in the hands of a few who in turn control a force monopoly so that those who are more productive than the norm can be coerced into supporting those who not as productive. So, if your society designers set out to eliminate the capacity for violence in the population you can't have a socialist system by definition.
Without the capacity for violence, you'd actually end up up with some kind of anarchist-libertarian society in which no individual or group could coerce another to do anything. All interactions would be voluntary and negotiated. Government, as it exist solely to manage violence, would simply "wither away" as one theorist once put it in his own flawed theory.
(Frankly, a lot of people would consider a world already a dystopia if they couldn't violently coerce others for the "common good". But I digress.)
But assuming the societies designers understood that no violence means no state and no coercive redistribution, they could try to ensure that a everyone got cared for in a non-violent society by engineering out sociopaths and then engineering the rest of the population to have high levels of empathy. With high empathy, one person experiences the pain of another and if confronted by a person in need, they experience that person's pain of want and give the other whatever they just to stop their own empathic pain.
(Of course, you have the classic problem of the "in the land of the blind, the one eyed man is king problem. If even a tiny minority could commit violence or lacked significant empathy, they could forcibly dominate the rest. There are several classic science fiction stories based on that premiss. We'll skip over that trope.)
But lets say your designers were careful did engineer an entire society of non-violent empaths who automatically and non violent redistributed the material wealth thye personally created automatically such that no one would go wanting. Well, it would likely be pretty nice...
For a while.
But if you did have automatic empathy based redistribution to make everyone at least materially equal, how would the society be able to build up surpluses resources to build new things?
For someone to have a have a house, someone must create and possess the resources required to build the house but forgo immediately consuming those resources. But if such individuals are such super empaths that they cannot withhold any surplus resources from others who have even a little less than they do, then all resources will be redistributed and consumed immediately and usable surpluses will ever accumulate.
In such a world, Steve Jobs and Steve Wozniack would never find the capital (surplus resources) to create new computers and if even if they did, they would never be able to hold back their first dollar of profits and all subsequent profits to build a company to make more computers. There would be no innovation, no creativity nothing new would ever get made.
For that matter, could the society stockpile even enough resources to ensure the repair and maintenance of existing resources?
I would say that your sunshine and puppies utopia society would turn into a dystopia as it first stagnated and then began to material fall apart.
The material standard of living would simply continuously decline. Thanks to redistribution, everyone would grow material more poor equally, but a society that landed in starships would find itself at a struggling preindustrial level in just a a few generations. People who try has hard as possible to mitigate the suffering of others but people would suffer and die horribly from disease, accident, natural disaster and eventually simple want.
For the super empaths, all the death and suffering would be horrific torture. Especially if they understood that for some reason, their ancestors did not have to suffer so. They'd feel the suffering of others as their own, watch children die in agony and and feel like they themselves were dying. They suffer that torment with every death and yet not be able to stop themselves to continuing the cycle of spreading out the declining resources thinner and thinner over fewer and fewer survivors.
At some point, they'd be faced with the choice of withholding the seed corn and letting some starve now so that the survivors could plant the next crop in the spring.
But their programming would not allow them to not feed the starving right before them. So, they'd eat their seed corn and in the next year, they could not plant any more crops and all their food would run out. They would kill everyone by sharing out the food equally such no one received enough to survive and everyone would would starve equally to death.
And the last super empath would feel it all, perhaps spending his final moments vainly trying to push the last crust of bread between the lips of a child whom the empath is to delirious to understand is already dead. His last thought as he tips over himself into the dust would be, "everyone was so smart, pretty and caring, why did we all die?"
A society of pretty, super caring geniuses who turn their entire world into a robotic extermination camp. Sounds like a pretty horrible dystopia to me.
