The wall is a smart move.
JP atmosphere in the park has always been defined by winding pathways and an all-encompassing tunnel/canopy effect from the trees, which obscures sightlines and contributes to the feeling of being very far from anywhere else (apart from the FJ building lol).
With the walls, that sense of broken-up views and us being smaller than the big surrounding environment is preserved. We still get the visuals of the coaster and rockwork because they rise above, and will get the same kinetic energy in the area when the train appears above walls, and I'm sure we'll get more greenery around the walls too. The thing to avoid in JP is big, open spaces which kill the mysterious vibe. This achieves that.
Edit -- Plus big walls mean a big gate. Petition for ceremonial opening thusly featuring a dramatic TM / guest each morning: