Why not just have everyone at Disney wear a birthday button? I mean, they were all born, right? What difference does it make if it's their actual birthday?
Me, I am going to Disney 9/13-9/21. My birthday is 9/6, so I will *not* be celebrating my birthDAY at Disney. I will be celebrating it at home with the cake my 9 year old will make me with her daddy from a box. (I will reap the benefits of my birthday by spending birthday gifts cards, though, and I will get belated birthday presents, make no mistake!) My son, however, will turn 4 on 9/20 so we *will* be celebrating his birthDAY at Be Our Guest and he will wear a button attached to his birthday shirt that reads "It's my birthday! Today I'm 4!" I do hope people make a big deal for his sake! I went to great lengths to be there on his actual birthday!
You can celebrate your birthday however you wish, it's a free country. Still, when people choose to make exceptions and celebrate a birthday on a day other than their actual birthday, it does detract from Disney's ability to be sincere and generous for the occasion. It's a numbers game. On any given day, maybe thirty people at Disney are there on their actual birthday, but when you take into account the people who are *pretending*, that number multiplies and thereby lessens the pixie dust available for the actual birthday people that day.
If I go to Red Robin on my birthday, they will give me a free meal if I show them my license proving it's my birthday. They will not, however, give me my free meal if I tell them "I couldn't celebrate last month because of XYZ, so I'm doing it now when it's convenient", they'll tell me to go fly a kite. It doesn't fit the numbers game.
So, while I agree that celebration is *always* a good thing and I embrace joy and cheerful, positive thinking.... If you pretend it's your birthday at Disney, you make it less possible for Disney to be more generous to those who are actually there on their birthday. Numbers, plain and simple.