I dunno about the fade theory - but the fact is that flash ruins the "show" for both you and for other riders. Flash washes out the colors that are very carefully chosen for the attraction, and is annoying to everyone else. When you print or develop your photos, you will find that all of the color is drained from them and all you are seeing is what is lit by white light. Many of the attractions are painted and specially designed to be lit by different colored lights that bring out the effect wanted. Take a flash photo of a special effect (like projections on fog) and you get nothing but white light on smoke.
As to non-flash photography, the only rides you are not allowed to video tape or photograph are the ones where you can not be in complete control of your equipment, or those that are copyrighted videos (Philharmagic, Star Tours, Honey I...Soarin'). Soarin' combines both - your inability to guarantee complete control over your equipment, as well as a copyrighted movie. Test Track is liable to send your camera flying - as is Tower of Terror, the roller coasters, and motion simulators. The rule of thumb here is not whether you personally think you can control your equipment, but if anybody thinks you can control it. Your wrist strap breaks when you are walking around Downtown Disney, you drop your camera, nobody gets hurt. Your wriststrap breaks while you are trying to videotape Big Thunder Mountain, you hurt the person a few rows behind you when your metal camera bonks them in the face. You really have no choice there but to keep your camera in the bag and safely tucked under your feet.
The reality is, that none of the attraction images belong to you - they belong to Disney. You are not, for example, permitted to print and sell photos of the castle with the fireworks behind it professionally. You are welcome to take the photos for your own use, but the image belongs to Disney. OF course, if you pay the royalty fee to Disney, then you can sell as many as you want, under contract to Disney.