Knott's started this whole trend in the 1970s. They called them mazes then, I'll still call them mazes now. It's probably a west coast thing because of the long history of Knott's.
While I personally dislike this move, I can see why Universal would do it: not only would it add synergy to both Universal coasts, but would also distinguish it from Knott's.
Old habits die hard, and there seems to be no harm caused by continuing to call them mazes casually. At the same time, I won't attack anyone for calling it a house. To each their own.