The point the OP is making is that given the choice parents will always choose a 100% 'perfect' child who will live a happy and long life free from things that make it difficult. Until relatively recently this hasn't actually been a choice though - as much as you'd like that, you've not been about to tell much about the long term future of a foetus so you got what Mother Nature blessed you with.
Increasingly though, parents can check, and they are doing, and that means they're getting to pick whether or not to carry a not-quite-perfect baby to term. Many are choosing to terminate and try again. Right now it's for obvious things like Downs, but the scope for what parents choose to terminate can, and probably will, escalate to other detectable problems.
The question is where that ends. Terminating due to a susceptibility to aggressive cancer? Maybe. Due to lower intelligence? Perhaps. Lower physical strength? Probability of autism? Unsymmetrical facial features (e.g. 'ugliness')?
Increasingly though, parents can check, and they are doing, and that means they're getting to pick whether or not to carry a not-quite-perfect baby to term. Many are choosing to terminate and try again. Right now it's for obvious things like Downs, but the scope for what parents choose to terminate can, and probably will, escalate to other detectable problems.
The question is where that ends. Terminating due to a susceptibility to aggressive cancer? Maybe. Due to lower intelligence? Perhaps. Lower physical strength? Probability of autism? Unsymmetrical facial features (e.g. 'ugliness')?