You've highlighted an excellent point here : it's nice for flight attendants to banter with the passengers, to build a rapport and to enjoy a laugh and a joke. They just have to be careful to ensure that those the joke/banter/laugh/rappor building is aimed at KNOW that it is such, and not a rude or inappropriate remark.
It's amazing what power a smile can posess. It could have turned this situation in to something completely and utterly different; a bit of fun that could likely have had the opposite kind of halo effect - making other passengers laugh and giggle.
I love to joke around with passengers. I know how far I can push it without overstepping the line. I can on occasion be rude, smutty or insulting to a passenger but with a grin on my face from ear to ear, the passenger knows that it's not meant and I am often treated to the same in return. If it's done the right way, things like this can really help make the day of the crew and, indeed, of the passenger.
Thanks for your observations and also, thanks for not taking it up with the crew on the flight. This could have taken the situation to places that nobody would really want to go to.