I agree that if your child is old enough to comprehend what was said in this commercial, then they're too old to be believing in Santa, the Easter Bunny, and the Tooth Fairy.
I was younger than ten when I found out "the truth" and I can say with all honesty that I wasn't particularly traumatized. I had started to figure things out when I noticed that Santa's handwriting was exactly the same as my mothers and that Santa used the same wrapping paper that we did. So when the other kids at school said something, it made complete sense to me. Although, I have to admit that I kept putting the baby teeth out long after I figured out the truth about the Tooth Fairy just to get the money.
I also agree that there are way more important issues that we should be worried about than one stupid Wal-Mart commerical.