Do you mean, what do people miss that used to be at WDW?
Horizons, The Great Movie Ride, If You Had Wings (aka Dreamflight), original (before Ellen version) Universe of Energy including pre-show with projections on rotating blocks, the Pleasure Island nightclubs (especially Comedy Warehouse) and the nightly New Year's Eve celebration, the Osborne Lights, the way all of Epcot's Future World used to be educational as well as fun, and all the songs they used to have on Future World rides. I miss the tunnels with projected images that some of the old rides used to have. I miss when you could show up for a day at Epcot and talk with a cast member on a video screen and make same-day dining reservations at any restaurant in the park. I miss the Main Street Electrical Parade, or even having any nighttime parade at the Magic Kingdom outside of party nights.
Also miss when the WDW resorts were not as expensive; when they had free parking for people staying there; when WDW overall IMHO had a stronger culture of high quality customer service (as many cast members still do, but IMHO it's less pervasive than it once was); when the park restrooms used to be consistently clean; and when all the indoor rides had air conditioning that felt cool enough.