> everyone will race to have the same set of (currently) desirable traits

I think it is not the case. Just on Earth you need different traits due to different climates and life conditions. Once we start really colonizing our solar system what makes humans better on some rock will be different for another or just for space: weaker heart, better bone density, some myopia could be useful to limit the currently known effects of 0G.

I find the argument about reduced diversity to be way too optimistic (or pessimistic ?) about people’s will and might to change their genes.

To draw a parralel, esthetic chirurgy is wildly available at relatively reduced risks, and it’s not like every bloke and their dog goes to have a face lift, even if it’s understood that a better appearance would have benefits.

Or even thinking about the core group of people who refuse to vaccinate. There’s just no way a medical practice is applied to the totality of a population, even by law.

  it’s not like every bloke and their dog goes
  to have a face lift

Right, but society has a conflicted history with beauty - some parts of our culture like and reward beauty, other parts curse the vain and superficial - and especially with people making uncommon efforts to improve their looks.

Not so with being born charismatic, tall, smart, healthy and with a full head of hair.

Exactly, just look what happened with dog breeding and how many breeds now suffer from significant genetic defects due to trying to breed desired traits.

The defects are largely a result of the limited capabilities of the breeding process (cross animals with a trait, hope that not too much other stuff comes along for the ride).

A fun angle: genetic engineering will eventually enable us to correct many of the problems in purebred animals. They are often good targets for even a limited genetic engineering capability (where the pure bred population has a high frequency of a single defective gene).

Some of the problems with dog breeding are due to the inefficiency of he breeding process, but others are simply the direct biomechanical consequences of the desired traits; for example the neotenous compressed faces of many lapdog breeds have consequences for mastication, respiration, and orbit shape that can't really be addressed without relaxing our selection for that particular look or accepting other tradeoffs.

hasnt diversity already been reduced by transportation? didnt it prove to be a bad things for american indians?

The opposite is true - transportation has increased diversity. The American Indians suffered due to a lack of exposure to diseases (smallpox) common in Europe due to their relative isolation

Erm ... that's also a way to put it. Another way to put it, they would not have suffered if not for rapid transportation.

But genetic diversity did increased - through mating.

a lack of diversity is only really bad in a changing world. however humans have made the world far more stable than before, and as we move our civilization into space, we'll find likely more stability (in the long run)

> humans have made the world far more stable than before

You must be kidding. Humans have changed their environment almost beyond recognition. We may already have broken ourselves, look at birth rates in the most industrialized countries.

The potential disasters can be man-made as well. Therefore, even though we're increasingly better at taming the vagaries of nature, we're increasingly at the mercy of our fellow men.

"as we move our civilization into space"

That is pretty optimistic

We can't even make it on Earth without horribly fumbling it, how would moving out to dead rocks help?

This is how we play for time, this is the whimpering with which we fade out. Looking straight at the iceberg, saying "it'll probably transform to cotton candy if we hit it fast enough". The drunk captain and the armed guards letting no sane person near the bridge is how you know everything is fine.