One point of perspective....
My dear Corey went to WDW about 100 times before she and I met. She grew up in FL. She never knew about park tours, character meals, free movies at FW, carriage rides, fireworks cruises or 90% of the rest of the stuff that is offered to WDW guests. She knew about the park rides. She knew about Grad Nites,
MNSSHP, and
MVMCP. Her family ususally packed lunches from home and therefore she rarely had a meal on property.
Kids know what their parents tell them about. If you tell your kids about the character meals and sell it to them as the coolest thing ever, then yeah, they are going to be disappointed when you can't book it. But, if you let information get to them on a need to know basis of what you are capable of delivering, then they only know the magic that they are presented with from the basic experience and are not hurt and disappointed when the other stuff never happens for them.
This is not to say that I don't know that that hurt feels like. When I was 4 years old, I went to MK for the first time. It was "sold" to me by my parents as Mickey's Home. I fully expected to meet Mickey. I didn't. I carried around a hurt feeling for 30 years. Yes, it took me 30 years to actually go on my own and be able to meet and hug Mickey Mouse. It was the most awesome feeling ever to make my sad little inner 4 year old happy.
Ramble over, but I just don't see why parents tell their kids about stuff that they may not be able to deliver on.