Haha, I see what you mean... but I still have to completely disagree.
Disco Yeti is still there, and the 90% of people who never rode it originally and aren't theme park fans don't even notice that it's not moving. Like it or not, the strobe effect works. The ride experience is largely the same, except for those of us in the know about the yeti's former state.
Meanwhile on FJ, it's super obvious that the willow is supposed to move, but it's not. Even the least observant of guests notice that they're rolling around and dodging absolutely nothing, all while watching the vicious tree from the books/films staying absolutely still. All the while, you can clearly see backstage elements that completely take away part of the greatness of the ride.