And that's exactly what's too reductive. The question is not about what the character is "doing." Again, any given storyline for a character can be handled very differently by different filmmakers. You're trying to reduce the question to a single variable, but there are many different ones that go into making a film work or fail. The character's actions are the least of it. If the filmmaker doesn't understand why the character would perform those actions, if the filmmaker doesn't respect the character's worldview and tries to show it as fundamentally futile or invalid, then that filmmaker's depiction of those actions will be completely different than if they were depicted by a filmmaker that understands and respects the character and his ideals.
As for what doing a Superman-style story right looks like, go turn on your TV and watch Supergirl. That's just about the best Super-universe screen adaptation I've ever seen.
"...and who, disguised as Clark Kent, mild-mannered reporter for a great metropolitan newspaper, fights a neverending battle for truth and justice." Seems pretty clear-cut to me. (The "American way" thing was only added during WWII, and revived for TV in the Red-scare '50s.) Superman is the archetype of superheroes. His goals are the most basic and universal goals you can get in a heroic narrative. It's not complicated to define.
The problem is when the people put in charge of making a Superman story are too cynical or jaded to have faith in such straightforward Boy-Scout heroism and feel they have to deconstruct it or apologize for it. This is why Supergirl works -- because it believes in its hero's basic optimism and demonstrates why it's valid and valuable.
