Obstensibly, the current Journey into Imagination is a partial "change back" since Figment was not part of the ride just after they added the Eric Idle stuff. However, there is really little point to changing anything back completely: There are so many great ideas out there that deserve a turn. Once something is gone, it makes more sense to try out a new idea than to spend all that capital rebuilding something which wasn't popular enough when it was demolished to stave off the wrecking ball.