Gattaca – Alternative Ending (1997)
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Genetic manipulation need not result in class and genetic discrimination and eugenics existed before many advances in genetics were made.
Compare with "Brave new world": genetic manipulation as a result and a tool of a classist and discriminating society, not the cause. Of course, BNW is different in other ways.
I still love the movie because of its many other themes - bravery, perseverance, whether you should be prevented of taking risks. I would still recommend it to anyone.
In addition, all the great people who were never born because their pregnancy ended in a miscarriage due to a lethal mutation: perhaps they would have made all the difference?
But since you're presumably asking whether we should consider a mutation to be good or not, that's really the same as asking whether anything is good.
Is blindness good, for example? I'd say not, but others may choose to blind themselves if it makes them happy. But I doubt most people would welcome a genetic mutation that blinded them.