Since the beginning, DISNEYLAND had been trying to figure out a way to make Tinker Bell fly above Sleeping Beauty Castle the way she did on the Disneyland TV show.
At the time, the Matterhorn was not in place to create a launching pad for the pixie's flight, so the original plan was to have a radio controlled Tink that would fly before the fireworks show. Testing never went well, once famously taking place in front of a bar that was next to Disney's Imagineering offices at the time. When the test pixie flew too high, she lost radio control and horrifically crashed into the pavement, causing many of the bar's denizens to call it a night.
The park's legal team wouldn't permit a radio controlled Tinker Bell for liability reasons, so once the Matterhorn sprang up, it became the launching point for the pixie's nightly flight.