Wierd (and it
physically hurts to write it this way) isn't completely wrong here (I actually agree with you to an extent, but we're too late). He's right, evolution is sweet, humans are short sighted and make mistakes. But, as others have pointed out, evolution is imperfect, and the "just good enough" nature of evolution isn't always nice. Frankly, our intelligence is against evolution, our brains have so many neurons because we discovered cooking makes digestion more efficient. We already live in a world where evolution has lost control.
Human "evolution" has already degraded. We don't choose partners based on benefit, we choose based on a shortsighted desire, either our happiness or for a fun time. Evolution can hardly influence who is the most fit, because we have found artificial ways to overcome evolution. Weapons provide safety from predators, housing provides safety from the elements, and we're quite good at protecting from disease. Antibiotics have saved tens or hundreds of thousands, but water sanitation has saved more lives than all doctors in all of history. We craft our environment, and we do it well. Human "evolution" now is controlled by the advancement of technology, which is completely dependent on 2 things, random genetic transactions producing bright people (which means we aren't getting more intelligent), and our artificial environments inspiring the next generation of engineers and scientists.
Evolution has already failed us, we're already our own destiny, and that's scary. I'm all for the advancement of technology, trust me I'm an engineer, but how many mistakes has mankind made in the advancement of technology and shortsighted goals. Will control over our genetic future be a bad thing, probably, but its better than the stagnation and degradation we already face.
How are we to protect ourselves from potential elitism? No idea. I suspect it would involve the same protection against it we've always used, lowering of prices through efficient mass production. Why should rich people get all of the strange body parts when *Insert medical company here* contains potential modifications at economical prices? How long before some become popular enough that hospitals or insurance agencies subsidize them? And what will we do when we need traits from a long dead pathogen? Buy them of course. Is this the right path? Who can say, but our evolution has been dependent on technological revolution, why not allow our genetic future to follow the same? Stagnation is just the same thing as waiting until we die, evolution is running from the inevitable regardless.
Personally, I think "open sourcing" "gene-engineering" is one way to protect ourselves. The right to bear arms is nothing more than security through freedom, which is the same principle open source is built on. If we can open source 3D printing, we can, in the future, open source medical treatments. And again, it might be dangerous, but so is living in a country where anyone you meet can be armed, the nature of life is surviving despite less than ideal situations. Its no more dangerous than a world where any script kiddie can get your personal information because someone found a vulnerability and open sourced its exploitation.
TL;DR: Evolution is meaningless, we already control and influence our environment without thinking everything through. Genetic engineering just brings our genetic future up from perlin noise. Nothing will safeguard life, evolution is fallible, everything will eventually die regardless. Think about how to prevent elitism and centralization of power, not how to make the world perfect.
Edit:
...Babies that are born with basically no cognitive function should be left to die...
I would just like to say babies are born with no real cognitive function. They have no consciousness and aren't self-aware. We have robots that are more sophisticated than a baby, at birth. Of course it grows, they gain consciousness and become self-aware, and eventually do stuff our coolest robots can't. But at birth babies have more in common with ants than people. That's not to say we should kill babies because we can, just a point. I'm also not disagreeing with you.