Why Are Movies and Novels Worse the Second Time around?

I bet there are counterexamples, but usually movies and novels are not as enjoyable when you watch/read them for the second time as they were the first time around. Why? I'll start with the obvious and end with the (hopefully) nonobvious.

1. Experiencing something for the first time tends to be more intense than the second, third, etc. experience. I wish I could recreate the sensation I felt when I first heard "Smells Like Teen Spirit". I can't.

2. (Not quite the same as the first point:) Some of the enjoyment you get out of a film or novel is based on surprise; naturally this doesn't work the second time around: You already know the jokes and who the murderer is.

3. For simplicity's sake, let's assume that 1 and 2 are not true. You will enjoy a given piece of art to varying degrees depending on when you consume it. One can think of the amount of utility that one gets out of a work of art as a normal distribution around a mean which one could call the "natural" level of utility to be gained. So, if you watch two films that are both "natural" sevens, your actual level of enjoyment may be six with one film and eight with the other. If you watch both again, the best guess is that your level of enjoyment will be seven with both. But which film are you more likely to watch again? Exactly.

4. This problem is exacerbated by your tastes changing over the years.

In other words, I recently re-watched Platoon and wasn't impressed.