Perhaps, and this may sound crazy to us, but perhaps, marketing is happy with the current rate of vacationers visiting the parks. And, (while the mouse down the street doesn't seem to mind dealing with it for Star Wars,) Universal Orlando knows they aren't prepared for, or willing to deal with, a massive onslaught of new guests this summer lined up to enter Hogsmeade again.
Promoting a new ride at the Wizarding World in the weeks leading up to its opening will do what it needs to do to create interest for people scheduling holiday vacations, or vacations next year, but will also ensure they don't get too overcrowded for the summer.
Word is from folks in the know, Orlando marketing seems pretty happy right now with where things are.