I was thinking there might be two reasons for doing this.
1. It would be nice to free our kids from birth defects, inherited diseases, and other characteristics that diminish their lives.
2. While I am a Christian, I also believe in evolution. But it seems to me that maybe evolution has been stopped in humans. Evolution is dependent on survival of the fittest. Which means that the less fit are weeded out and prevented from entering the gene pool. In Nature survival is rare. For example among salmon only a tiny percentage survive long enough to spawn, about 1 in 1000 as I recall. So only the best of the best are able to reproduce and pass their traits on to the young. Even among Lions, the king of the beasts, survival is the exception. Less than half reach maturity. The weeding out process eliminates the weakest half. This was also true among humans in the past. But because of modern medicine, survival is now the rule for human children. This is undoubtedly a good thing from the perspective of giving everyone a reasonable lifetime. The disadvantage is that if everyone survives then the weeding out process cannot work. Maybe genetic engineering offers a way of preserving our desireable genes and even advancing them, without the unpleasant effects of the weeding out process.
Its just a thought, and maybe I'm out to lunch.