I was pondering further over lunch and came up with this scenario
So you are the MD of a new airline, amongst all the other bits you need (aircraft, sales, routes etc.) you need crew.
So how many do you need and why?
Flight deck, well you need a pilot, but you think well trains and other forms of transport only have one driver, but you need two on the flight deck for passenger safety and because various legislation tells you you need them.
Cabin Crew, well you only fly short sectors, ground staff can get folks to their seats so why do you need cabin crew, for safety reasons and because legislation says you do.
Fine, now the flight crew have to be "locked" in by legislation so rarely are seen by the passengers. In fact the only evidence they exist is if they are seen through the F/D window on boarding and in the form of disembodied voices on the PA system.
So you've got some employees in the cabin, legally they are there to ensure passenger safety so, in theory, could sit around during the flight doing nothing else.
Ah, but you think, lets give them something else to do!
Lets get them to give/sell food to the passengers
Lets get them to sell duty free to the passengers
Lets get them to manage the IFE system
as if we do this it might encourage passengers to fly with us again.
Silly I know, but at the end of the day the prime reason crews are on aircraft is to ensure your safety not to serve your every need - a fact that a lot of passengers either don't know or if they use this site seem to forget