As Martin mentioned, people keep coming and riding, so they see no reason to put anymore than the minimum into it. Most guests don't complain, so nothing's going to happen. This is reflective of the new Disney norm - Good enough is good enough, if you can raise prices, do so, and anything big, bold, or requiring CapEx is either highly, highly scrutinized for ROI or just forbidden because it's "risky". IMHO, improving Space Mountain, or even making the ride itself decent again, won't happen as long as Iger and Cheapek are around.