What is the point of having a menu?

On the 11.06.2015 and the 27.06.2015 my partner and I flew Etihad airways flight EY 603/EY604/EY 41/EY 48 and EY 604. It was exciting for us as it was our first time overseas together and the first time we had flown Etihad, we had the option between Etihad and Emirates as either of us have always flown Emirates but decided that we would try Etihad ,on all four flights we were situated at the back of the planes and on all four of these flights we were handed a menu, but I don't understand why menus are handed out when the air hostess comes to you and serves you your food only to tell you that two out of the three options of food on the menu are finished so we had to eat what was left. It would have been ok if this was the case on just one of the flights but the fact that on all four flights we had to eat what was left is not acceptable as we pay for these flights just like everyone else. Two lessons learnt here 1.Dont sit at the back of the plane and 2. rather fly with an airline you know.