Irony machine: why are AI researchers teaching computers to recognise irony?

What was your first reaction when you heard about Blake Lemoine, the Google engineer who announced last month the AI program he was working on had developed consciousness? If, like me, you're instinctively suspicious, it might have been something like: Is this guy serious? Does he honestly believe what he is saying? Or is this an elaborate hoax? Put the answers to those questions to one side.