It is a good advert. My sister was an air hostess for Virgin for a little while and out of all the people who "got their wings" with her only one was male (was about 15 of them I think)..it is mostly females who become air hostesses, and that is their uniform...presentability and all that.
Nothing sexist about it, it's just an advert at the end of the day. They always have prettier people for them.