It isn't unheard of, but the cuts are far more severe than they once were. Also, the projects now often start out less amazing and ambitious to begin with. So when the debilitating budget cuts hit, there's not much left to work with.
Bellagio has its large size to impress people, something that Rivers of Light will be unable to match in its location. So it won't have the size impact. And World of Color has its well choreographed colored lighting, plus the clips and soundtrack. We can't say what will be affected in RoL's budget cuts, but it will probably impact a lot of aspects. Could be the tree's lighting effects, fewer fountains (that don't move as much), fewer and lower quality projections, less colored lighting for the water jets, and perhaps even things unrelated to the tech such as lesser quality music and visuals in the production process. There's a huge difference in quality between Illuminations' water jet effects and World of Color's, same goes for Fantasmic's mist projections compared to WoC's own mist projections. So even among seemingly similar types of technology there can be major differences in quality and execution.
If whylightbulb is saying the show will be nowhere near as good as World of Color, then i'm inclined to take his word for it given his track record (as well as Disney World's). The concept art looks like World of Color, so i'm guessing the cuts happened after the art was made and perhaps released. And if it's as serious as he made it sound, i'm worried.
Hard to ignore when your concept art is at least ten times more ambitious than the final product. Though it's much more than three posters taking notice and posting about it.
This. The original blue sky plans for the Mine Train were probably even more ambitious than the official concept art (we probably won't see them). Something like the sketch of New Fantasyland that had the boat running through it was a blue sky thing. The plans for the longer track were when a budget was already approved officially apparently. Cuts occurred after that and mandated a scaling back of the land and the ride.
How crude it was doesn't matter, it's more than enough to show us how much longer and more elaborate the original track length would have been. There were three versions of the track, each subsequent version shortened because the budget was cut several times. According to Lee and Martin however, the original track layout they posted was not unattainable at all.