Greg Cox wrote:
So I'm not sure why anyone would assume that the AVENGERS movie is going to follow the plot of the first issue?
I don't that is the assumption, at least not in so many words. It's more of a deduction based on what is known about the film and how Avengers' origin stories have been told in the past.
We're not going to get the story from Avengers #1, or the story from the original Ultimates run, but something involving Loki and a rampaging Hulk seems like strong possibility (though far from a certainty, of course).
Personally, I think that, in any event, a "Loki manipulates Hulk" plot would be more like a subplot in the first half of the movie while a bigger threat is looming, rather than the main plot of the film.