Don't we normally call that having children?
But the problem is that computers do what you say, not what you mean. If I write a function called be_nice_to_people(), the fact that I gave my function that name does nothing to affect the implementation. Instead my computers behavior will depend on the specific details of the implementation. And since being nice to people is a behavior that's extremely hard to precisely specify, by default creating an AI that's smart enough to replace humans is likely to result in a bad outcome.
Recommended book: http://www.amazon.com/Superintelligence-Dangers-Strategies-N...