I am wondering - are they doing this just so they can have a laugh at our expense?

I usually travel light. But occasionally I have a larger piece of luggage, (e.g. around christmas when i have a suitcase full of presents).

The day the check in agent tells me that I cannot check my suitcase in because it's heavier than 23kg, I will look him/ her in the eye, say thank you very much, cancel my booking, get my refund and walk over to any other airline that is happy to take me, my clothes and my presents all at once.

Again, this smacks of arrogance on BA's part - they might come to regret many of these policies come the next downturn.