I do see your point, but you're also talking about Pirates and Haunted, both buildings that enclose flat dark rides for the most part (rides that are going at most from the second, or WDW ground, level down to the first, or "Utilidor" level). Those show buildings are much easier to conceal from line of sight.
Even if they did some form of camouflage, you're talking about roller coasters that will be involving show buildings for most of the experience. They have to have height, a good amount of it.