I should note that specifically targeting the fans of the comic the best way to guarantee absolute failure. Simply put, there aren't enough of us to matter. So, an adaptation *has* to target the GA. Now, a lot of the time, a faithful, high quality adaptation *is* the best way to target the GA. . . but the people producing it need to have a good sense of what elements will be an easy sell to the GA, which elements are a harder sell, but necessary ( and thus need the most effort ), and which elements are superfluous. IMO, this is a big part of what killed Green Lantern.
Worst than that, that small fanbase that you mentioned can't even agree with each other.
Take X-Men, for example.
1) Who should be on the team?
2) Wolverine: Awesome or overused?
3) Magneto: Hero, misguided anti-villain, or completely evil?
4) Superheroes with flashy costumes or a military-esque team with realistic uniforms?
5) Fantastic adventures dealing with space aliens and time travel or a down to earth metaphor for civil rights?
6) Stuffed to the brim with characters or focus on a small team so each individual character can get more development?
7) Beast: Human, Classic Blue, or Cat Form?
8) Emma Frost: Hero or Villain?
9) Rogue: Ms. Marvel Powers or Not?
10) Jean Grey: Better off with Phoenix powers, better off without Phoenix powers, or better off dead?
11) Main Character: Cyclops or Wolverine?
Etc.
The fanbase can't agree on anything, so even if filmmakers do try to cater to them it ends up backfiring anyways.