To be fair to Universal, lighting schemes are changed generally park wide for the event. A lot of the lighting is either dimmed, or the colors are indeed changed. They even changed the lighting around the London construction zone last year (it was red). Some area's are better lit than others of course. Specifically speaking of the MIB/FFL area, the lighting is changed, but it's generally just dimmed. In recent history, they did add a prop or two with fog and lights, near the exit of the Sprung Tent during HHN XXII. With Springfield, they occasionally will play a version of The Simpsons Treehouse of Horror theme throughout the night. I'm not so sure random Halloween decorations will do much. Universal is more about the horror of Halloween. Disney is more about families. The Mouse focuses on the festive side of Halloween and the Autumn season itself- Jack-o-Lanterns, cornucopias, wreaths, typical black & orange colors, hay, fruit, trick or treating, scarecrows, and foliage. Universal is trying to scare you, and capture that mood in certain areas of the park. It's two totally different mental approaches to the holiday.