FTG,
You may be tilting at semantics there. The primary purpose, the reason for being, and the whole reason for being in the cabin by the cabin crew is safety.
Airlines use the cabin crew for additional services and benefits; they attend to the passengers and are thus flight attendants. However, the only mandatory reason they're present, and the entire reason they're required, is safety of flight. Neither the FAA, nor CAA, nor any other regulatory body demands the use of flight attendants as a cabin accessory or decoration...the flight attendants are there for the benefit and safety of the passengers.
The training of a flight attendant with respect to egress, fire, safety, and security isn't just an extra thing that waitresses and fashion models are taught. Rather, it's the core of what they do. It's the meat and potatoes of being a flight attendant. Serving sandwiches and drinks is the fluff...it's something they do when there's time...but it's not the reason they're on board.
Certainly airlines have at times sought to capitalize on the asthetic benifits of the flight attendant. However, if you travel very widely you'll find that internationally this isn't the case. In fact, I see more middle aged and older frumpy and reasonably unattractive flight attendants these days than I see sex symbols...and I see a lot of male flight attendants, too. When it comes to the safety briefing, of course, I don't care what their appearance; they get my full attention and support all the same.
The flight attendant is NOT eye candy, and is far more than a waitress that gives a briefing at the start of the flight. A nurse in a hospital may bring a patient a drink, but is a trained and experienced medical professional who performs additional, menial duties in addition to important life-saving ones. The same can be said of the flight attendant. If the flight attendant is attractive, one may certainly appreciate it, but it's really irrelevant.