I was raised Santa-free. Obviously I therefore have no basis for comparison, but Christmas sure seemed plenty magical, and I never had to get over the weirdness of discovering I'd been pointlessly duped by my parents. I did have to protect the innocence of the duped children, though, a duty I honored by total neglect. I told everybody. The ones who were only holding on in creepy obligation to parents wrapped up in the myth believed me. The ones who really believed thought I was nuts.
Anyway, I don't get it at all, which is to say I think nasty thoughts about parents who force their kids to believe in Santa. Parents and grandparents seem to derive some kind of sick glee from the deception. They always say it's about creating magic and wonder, but do they invent other jolly home invaders and insist maniacally on their existence? Generally no. I think kids would be a lot better served if the adults in their lives put some of that effort and enthusiasm into fostering delight in actual wonders -- in which this universe, thank God, abounds -- rather than lock-stepping along with this same hokey tale.
We all ask our kids to take our word for it that some things are not what they seem. Sometimes it's because our vision is simply wider: the stars are not little lights; they're huge suns far away. Sometimes it's because there are things in which we feel strongly they ought to believe: God, justice, the fundamental superiority of the Philadelphia Eagles to the Dallas Cowboys. But when you ask a child to believe you and not his lying eyes, you'd better have a damned good reason for it. You'd better believe it yourself, or no matter how cute, how precious, how magical the myth is that you ask that kid to accept, one day he's going to understand that you deceived him and feel like a fool for believing you. And then you're just an asshole.
(Edited to clarify meaning. Also to note that Andy Photoshopped the t-shirt -- it really reads "If Mommy Says No, Ask Santa.")