From an ideal standpoint it looks as if super-intelligent kids is something every parent would want. However there are some drawbacks. First, IQ is only a rough measure of intelligence, there are many factors involved and success in life is not immediately linked to IQ. See Unabomber, etc. Also super intelligent kids may not be that easy to handle. They typically hate school and may actually do poorly in school. They demand much more attention from parents (more activities, more time with them, etc). There is plenty of evidence that IQ is also linked to the environment kids grow in, so simply selecting the gene stuff and thinking this may be enough will not work. Intelligence is also linked to curiosity and independence and so perhaps to more risky behaviours. Finally there is a correlation with very high IQ and some severe forms of mental illness.
All in all, there is a cluster of reasons why the average IQ of the population is 100. High intelligence is not always that comfortable. Think of Sir Winston Churchill, hero of the battle of England, most effective Prime Minister in a time of war, Nobel prize winner in litterature. He had severe depression all his life (his "black dog"). I agree we should raise the general IQ though, cautiously.