The problem with Hollywood has several layers that contribute to the origin story fatigue issue:
1) Marketing
"Give me something I can sell" is the mantra of the salesman. Hollywood executives are in it for the money. Period. They don't give a flying fuck about the integrity of the story, character development, story arc, catharsis, or any of that artistic stuff that makes a good movie good. They think they can pay the rainmakers to make it rain craft be damned. If their marketing firms give them research data that says "teenaged vampires and werewolves is the sweet spot," they will make those movies. They are looking for projects that fit market analysis. When the average feature film marketing budget is $50M, your movie better be a rainmaker by their voodoo or it's not getting a green light for development much less going into production.
2) Branding
Because "the brand" is ever so important in our increasingly consumer-conscious pop culture, teenaged boys between 13 and 25 are the target audience for a "Brand" like Spiderman or any other comic book coming to the big screen. They will milk that cow dry and grind the meat for sequel burgers.
Here's where your fatigue starts to set in.
3) Lost in Translation
Production companies have become mills that hire production teams to crank out scripts for material we've already seen. (franchise fatigue).
The problem with comic books becoming movies is that the screenplay genre often generates a completely different storytelling form from the original work. Comics and graphic novels have a very unique and staccato language of storytelling that is negated by the transition to live action. The art of the comic or graphic novel is the craft of telling the story without telling you too much. This economy of words and pictures leaves much to the imagination--an abstract economy where the reader experiences the story in a world co-created between his imagination and the artist's craft. When you jump to to big screen, the viewers' intimacy of the details is hijacked by the director and the viewer is no longer an active participant. For this reason, I think adaptations of comic, graphics novels, and even regular novels will always disappoint those familiar with the prior art.
That said, producers, writers, and directors think that they can do better a better job than our imaginations so they keep trying to find formulas, remakes, reboots, and new origin stories to keep us interested when, really, it's already a losing battle for the reasons I posit.
This isn't to say that there are no good comic book movies--but most will agree that there are, in fact, very few in that category.
Audiences keep paying money to see movies they usually dont' like. We're enabling their behavior. Well, the 13-25 yr old males are anyways.