I think it's more about raising expectations by the general public. We've been handed a huge amount of detail and get biweekly aerial photos showing progress plus people at the parks almost daily, so even without a big statement from Universal, we're relatively well informed.
The general public on the other hand aren't. This can range from somebody having zero knowledge that it's even coming to somebody thinking this will be another Rip Ride Rockit. Letting people know that this is a huge ride, it will advance the story of Harry Potter with unseen locations and a new story while at the same time being an excellent coaster and possibly redefining the public's perception of what a coaster can even be.
If it opens for the summer, it also gives people a huge incentive to the people who maybe booked a trip to Orlando expecting Star Wars to be open to visit Universal.
Make no mistake about it, this is going to be #OperationHype.