I mean, in response to the last one, the Federation does allow (and sometimes advocates) for the correction of birth defects.
Julian: DNA resequencing for any reason other than repairing serious birth defects is illegal. Any genetically enhanced human being is barred from serving in Starfleet or practising medicine.
Deep Space Nine, "Doctor Bashir, I presume"
Doctor: Yes. It's a girl. And aside from the deviated spine, she's healthy.
Paris: Will she need surgery?
Doctor: Fortunately, we've advanced beyond that. Genetic modification is the treatment of choice.
Voyager, "Lineage"
So I imagine plenty of disabilities do end up being erased, it's just that being disabled is also socially accepted to a much greater extent than today.
He was born blind and remained blind until he got his first VISOR at 5 years old. It's in the TNG episode Hero Worship. His optical nerve was regenerating on Ba'ku but whatever his disability, it would eat away at it once he left the planet.
By the way, "again" in that context doesn't necessarily imply his eyes deteriorated before. It references the previous change, but that includes the improvement, not just some hypothetical previous instance of deterioration.
It's like saying "he went in the door, then he went back out again," which doesn't imply he had previously exited.
If someone in Star Trek is born with a bum knee, they just laser surgery the knee. Deformed backbone, replicate a new backbone. A lot of defects and disabilities can be solved by 24th-century medicine without involving genetics.
McCoy gave that old lady a pill and she regrew her kidney using her own aged body inside of an hour. Apparently, fixes of that type are an over the counter prescription and don’t run afoul of the eugenics laws either.
Approved genetic modifications is more for things like conjoined births or fetal organ failure. Too many toes? Here’s some special shoes, carry on.
But its also very human to let perfect be the enemy of good, or to do irrational shit like declare a style of facial hair forever associated with evil because one evil guy used it (As opposed to associating it with say a famous comedian) like we're afraid to say voldemort.