Who cares of it works better than being for complex traits? If it works as well as being for complex traits that's really great. Selective breeding can move a population mean about half a standard deviation per generation. That's not iterated embryo selection, just once. I would pay a
lot of money to be guaranteed a child in the upper 50% of what is possible with me and my girlfriend's genes.
If you want an illustration of the power of selective breeding contemplate the various breeds of dog. For a modern and well documented example see the domestication of the Silver Fox. It only took them six generations to domesticate them.
http://en.m.wikipedia.org/wiki/Domesticated_silver_fox
The least domesticated foxes, those that flee from experimenters or bite when stroked or handled, are assigned to Class III. Foxes in Class II let themselves be petted and handled but show no emotionally friendly response to experimenters. Foxes in Class I are friendly toward experimenters, wagging their tails and whining. In the sixth generation bred for tameness we had to add an even higher-scoring category. Members of Class IE, the "domesticated elite," are eager to establish human contact, whimpering to attract attention and sniffing and licking experimenters like dogs. They start displaying this kind of behavior before they are one month old. By the tenth generation, 18 percent of fox pups were elite; by the 20th, the figure had reached 35 percent. Today elite foxes make up 70 to 80 percent of our experimentally selected population.