Maybe that’s the eugenics issue. Correcting genetic damage might be small and rare. On the other hand if everyone wants a blond blue eyed baby that will grow up to be a 6’2” Adonis, genius, super athlete, then yeah

Only superficially. It's really hard to tell what percentage of our DNA is actually useful, or could be useful under conditions we haven't seen, or is actually a part of any given variation. What we do know, of the number of DNA combinations we have seen if we play out each possible version of those variations there's around 4^2000 variations. Or in other words If a billion people were born every day since the start of the universe, there would not be a single duplicate person. And this is the extreme low end estimate based on limited data sets that generally don't even include people of every major region, much less interesting micro-populations that have been breeding in isolation for a thousand years or more.

Now lets assume we remove all causes of congenital blindness. Generally speaking the number of genes making up most identified causes are less than 20 total. That would (simplified, yell at me later math nerds) knock that number down to around 4^1995.

That would still be more viable combinations than we could possibly run through from now until the heat death of the universe, assuming current population growth rates which we'll have until we invent birthing pods.

In other words we'll probably be fine, but if we need to, and it's allowed to be researched more, we could just simply artifically introduce safe variation. i.e. people giving birth to people they aren't genetically related to anymore.

No. Why? We could literally introduce diversity into the gene pool in a controlled manner.