It is suppose to be a little funny, a little flirty, a little naughty... (sex sells people!)
In my humble opinion - some are *overthinking* this issue.
I'd rather my FAs have this type attitude than most I see in real life.

I had to give a real time "thank you" to the Frontier FA who had the courage to tell a mother to get control over her toddler who was running up and down the isle after the seatbelt sign had been turned on during the descent.
A little admonishment for the obvious disregard of the rules and instructions given by the crew goes a long way (e.g. the deafening sound of seat belt buckles being unclasped long before the aircraft comes to a stop at the gate). Yes - we must all RUSH to be the first to stand-up and then wait for 15 minutes for movement!

USMCFLYR