A few weeks ago DD3 (aged 5) had just had a fantastic time at a schoolfriend's disco party - lots of dancing, games, party food, bags at the end, etc. etc. Loads of time, money and effort had clearly gone into the preparation. DD was probably being overemotional since the party was late afternoon/early evening, but she burst into tears when she got into the car, peeped in the bag, and found it did not contain a piece of birthday cake (she didn't get a piece and I don't think anyone else did, either, but DD thinks she was the only one!) It might have been an oversight, but the biscuit which was there would suggest not.
Gosh, this makes her sound spoilt and me ungrateful, but the point I am trying to make is that the thoughtful tradition of sharing the birthday cake is appreciated far more than any amount of costly entertainers, elaborate decorations or sweet-filled party bags! I've always kept a spare (iced or chocolate-covered but undecorated) cake in reserve to cut up just in case there wasn't enough to go around. It never goes to waste!