Hollywood is a land of money and cowardice. Every big film is basically a $150 million gamble, so they tend to play it safe and stick to a successful formula.
Nowhere is this more evident than in the genre of big-budget superhero franchises, where it's been decided that you must follow most if not all of the eight rules below:
8The First Film Requires a Tedious Origin Story
For some unknown reason, tradition states that the first movie must consist largely of something no one in the audience paid to see: The superhero as he lived before he could do any cool superhero stuff.
Other genres don't feel the need to do this; Die Hard didn't spend the first half of the movie with John McClane taking target practice, Rambo didn't spend an hour showing Rambo in basic training. Why can't we just jump in?
Instead we have to watch Peter Parker struggling as a photographer, and Bruce Banner quietly working as a scientist, as if we must first appreciate the tedium of their regular lives before we get to see them jump off an exploding building.
And to double the problem, they usually throw in an origin story for one or more of the villains, too. Behold! Here is the awesome badass supervillain, back when he was just a disgruntled dude in a lab coat!
Often to save time they'll cram those two origin stories together, by having the main villain kill off the hero's parents (regardless of whether or not it happened in the comic book) simultaneously starting their respective careers in superheroism and supervillainy.
A young Joker kills Bruce Wayne's parents, Robin's are trapezed to death, Kingpin kills Daredevil's dad
In Spider-Man 3, the previous origin story is changed so that the current villain (The Sandman, Marko Cain) is now the murderer of Uncle Ben, a plot point based entirely on the premise that none of the fans owned a DVD of the first film.