People like to complain. It’s not even remotely a rough coaster compared to plenty, especially at its age. The cars aren’t rickety, they don’t bounce around, they dont rattle. The worst it is is jerky, and that’s more due to people not knowing where the turns are in paring with the seating style. Most coasters of its style are out in the daylight so people can brace for the turns. Matterhorn is much rougher, but because you can see the track, it has no jerky surprises, and that ride isn’t exactly a rough one either.
People are just expecting a wild mouse coaster in the dark to feel like Slinky Dog and Everest, as that is now their expectation having ridden only super smooth coasters at Disney, when that just isn’t the type of ride it is.