Isn't the whole point of Terry Prachett's works to create witty and endearing satire? I always read his books as him looking at our world and reality through the perspective of a very intelligent, childlike mind, that questions and rejects our world as for being nonensical and through Discworld, he makes a world that makes a lot more sense even if it appears absolutely bonkers. To Discworld, we are the weirdos. That is what I really enjoyed about his books. He forces you to think about the absurdity of our reality by asking frankly ridiculous questions and then through his clever storytelling and social and political commentary, he always manages to deliver a well thought out point that makes you appreciate all kinds of facettes of life.

In the case of Terry Prachett, the theft of ideas is the entire point and not a natural bi product of being a creative.