Hell, I could make the same argument for the Superman movie (the 1979 one) where the "big reveal" of Superman comes after probably almost 30 minutes of story build up when Lois is in the crashing helicopter.
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That's a judgment call. I love the Donner movie, but I also have vivid memories of taking my little brothers and sisters to see it. Long before the Fortress of Solitude, they were all squirming impatiently. "Where is Superman?"
Not an unreasonable question.
The problem with extended origin stories is that the first movie often ends up feeling like an extended prologue to the movie you really want to see. Which may explain why the second film in a superhero series is often the most popular. The origin stuff is over and they can finally get around to giving you a full-length SPIDER-MAN movie or whatever.