1. I believe the pastoral past is often viewed in a utopian light because it emphasized traditional values. By eliminating various freedoms which society has come to embrace in modern times, there was less ambiguity in the path of one’s life. Religious values, or otherwise values maintained by the collective society, guided every single action made by its members, and deviance was handled in strict terms with ostracizing and harsh punishment. I feel the utopian view, then, comes from the seeming security of purpose—truly a damaged view of agrarian life, however, as it ignores uncontrollable variables that often meant suffering and death for its peoples. Medicine was relatively arbitrary; many illnesses which are commonly cured today were completely untreatable and often fatal, and without rigorous scientific process, new treatments never came and questionable folk treatments were emphasized. A lack of knowledge and tools regarding climate and farming meant crops could be easily lost, depriving farmsteads of sustenance or income. Justice was, again, arbitrary and sometimes barbaric. Without precise methods of investigation, accusations could be freely levied, and claims couldn’t be adequately appraised. Superstition and references to the metaphysical were commonplace, and often led to deception and hardship when applied.
In short, I don’t view the pastoral past as particularly utopian, but I understand its appeal to some if you ignore its more harmful aspects.
2. Unfortunately, I’m a little biased in answering this question; I write fantasy in my spare time, so my answer is kind of clear.
Through fantasy’s ambivalence to history and reality, I believe it appeals to a related utopian impulse, complete and total freedom. When writing fantasy, because of that ambivalence, an author has infinite freedom on the page while writing, and a reader can expect that freedom to reflect in the reading. The genre has come to be defined by common imagery (on the surface level of this, think elves, dwarves, orcs, dragons, magic/psychic powers, etc.), but in any given fantasy narrative, there’s never a guarantee that any of these common factors will appear; an author could try to create something entirely new, as is often the case in high/epic fantasy set in alternate worlds like Game of Thrones and The Inheritance Cycle. Fantasy is simultaneously a playground and a gymnasium for the imagination, whether writing it or reading.
Though fantasy is my favorite, I also feel similarly towards science fiction, and so I tend to view both fondly. Science fiction tends to be connected to the past and present, but depending on the future an author imagines, the links can be quite small, and you see almost as much variation in different science fiction entries as you do in epic fantasy. In a similar way, it offers a mental escape, freedom, and exercise, though sometimes just to a lesser extent than fantasy.