I wish you were right, but I have my doubts. Some people familiar with writing software think the DNA is some type of very long program written in some unknown language. If only we could decipher the language. In reality, there is no language. The genes are recipes to build some nano-machines (the proteins). That's it. Some of us posses a certain version of a protein, some posses another one. Everything is emergent properties. It's like positing the rules for a "game of life". You can't tell from the rules what emergent behavior you'll see. You need to run the game. Evolution does just that, it runs the game. Some codes survive, some don't. There is no language of the genetic code.

For us to fine tune inteligence or strength, we need to be able to predict lots and lots of layers of emerging properties. Or simply to find ways to run the game many, many times. We can't run the game by experimenting with babies. Will we be able to run the game on a computer? I'm not holding my breath on this one.

I wouldn't call that pessimistic. Fine-tuning traits like intelligence, strength, height, etc are in my opinion the thing that's going to lead to designer babies. The longer we stay away from that, the better.

I can certainly see the case for fixing genetic defects, though as the sickly cell/malaria example shows, that's not always clear cut either. And even if you just fight genetic defects, if it's only available to the rich, it's going to create a genetic class system where the rich literally have better genes than the poor. I shudder to think what that might do to a society.