>>42355825 (OP)Because the utopian aspect is not inherent to their biological being, but in the way they treat each other. Unlike in this rotten, wretched world, ponies treat those who are less biologically advantaged with the same respect and decency they give to abled members of their society.
In essence, ponies want to work on creating a world full of happiness, unlike humans who actively work on creating a world full of strife.