I like the idea but I find the ears themselves to be expensive, ugly and nigh-unwearable which ultimately destroys the idea.
Smaller/cheaper ears with different hat styles that can easily fit on a child's head so more people would wear them would greatly help them.
Heck, making OTHER non-ears devices that glow in sync with the show would be just as cool (fairy wands, wishing stars, swords... light sabers!)
Or heck, since they're rebuilding the hub anyway - how about LEDs embedded in the concrete to light up in sync with the castle!