People wanting to better the Human condition through genetic engineering aren't the ones causing suffering. For the better part of a century now, our medical technology has been allowing people who would never have survived into adulthood to do so and have children. Our welfare programs have been allowing people incapable of supporting themselves to have large numbers of children. Children who are just as ill equipped to survive on their own, whether through biological or social factors, as their parents.

On a side note. What happened to the race horse may not have had anything to do with genetics. It may have been a simple case of pushing an animal beyond its limits. Having a horse run at full gallop for a long distance with 120+ pounds on its back on soft wet soil isn't a natural act.