Now, Diagon Alley and Gringotts, promise to be amazing, but no need for these silly wand things, that wont worth properly anyway.
I'm sure the wands just emit an infrared or something that sets off sensors in the windows. Same as the guns in the shooting gallery at MK (or pretty much any "animated" shooting gallery anywhere).
You also can have a line of kids doing Agent P's or the Sorcerers game at WDW. Is it going to cost me some money for the kids to get their new wands yes. Is it going to make them happy of course it is.
It seems Universal is actually trying to make the guest be immersed beyond the ride aspect and also make a tidy profit.