The question is why? The answer to that is because it is logical and therefore natural.
Intelligent beings creating intelligent things makes sense because their creations were created to serve a purpose which means they were created for a reason. Therefore it is logical for intelligence to create intelligence.
And because our creations serve a purpose and because it is natural for intelligence to progress it is natural for intelligence to create ever increasing intelligent creations.
And since this is what we see, it’s kind of hard to not reach the conclusion that creating intelligence is an artifact of intelligence.
You said that intelligent beings create things that become more and more intelligent. The question then would be is it possible for an intelligent being to create something that becomes more intelligent than the creator?
In the case of mankind, we are very close to quantum computing, and many scientists have said that would be very close to how the human brain operates. That being said, could a quantum computer "evolve" or be created that is smarter than mankind?
That being said, is it possible for mankind to evolve to the point where they can be more intelligent than God? Or, do you think He put in a fail safe in us, keeping us from becoming as intelligent or more so than the Creator?