Ask yourself, what TV commercials have you seen that you remember, ones that were dry and witless, or clever ads that delivered their content in a entertaining manner.
People tend to remember stuff that they find relevant to them. If they enjoy something, they also tend to remember it.
How many pax have you seen when you've been travelling just ignore the passenger briefing and keep reading their paper. Hit them over the head with a briefing that makes them sit up and notice, making them ask themselves what is it that everyone else in the aircraft finds amusing. They'll probably then end up paying attention to the briefing instead of finishing reading section one of the Herald.
Sure I agree there is a limit where the original content shouldn't be diluted down in it's importance, but I hardly see the harm in these announcements as the original message is still there.
Just because it's a different way of doing things, doesn't make it the wrong way of doing things...