It's harder to get away with giving humans hip dysplasia because they live for a long time and can complain about it. Gene modification also doesn't work by res

It's harder to get away with giving humans hip dysplasia because they live for a long time and can complain about it. Gene modification also doesn't work by restricting the number of breeding pairs, so your complaint (while valid for dog breeding) doesn't apply to human genetic health improvement. There is a related risk in the form of reducing genetic diversity, which can increase population-level vulnerability to infectious diseases. However, it's unlikely that the kind of modifications people will first use (strength boost, intelligence boost, better heart health, etc.) will pose a serious risk in this respect. I would advocate extreme caution for large-scale modification of immune system-related genes.