Hmm. Yknow, been thinking about DCUO and Skyrim, and Regan the suicidal girl from All-Star. DCUO has random NPC's around Gotham and Metropolis; suicidal jumpers you either talk down or push, depending on whether you play a hero or villain, people trying to rob ATM's, etc. And Elder Scrolls often have "hidden" mysteries and objectives that aren't part of any mission chain or goal, but if you find all the clues (which aren't highlighted for easy location, you actually gotta look for them) you usually find a cool/fun reward too.
Maybe a Super game needs something like that? Maybe a little kid lost their comic collection, and you'll find them scattered around town (not highlighted in any way so you can easily miss them), maybe you need to use an Elder Scrolls style "social interaction" menu to talk a jumper off a ledge. Stuff that encourages you to use your super senses and leans into stuff like Elder Scrolls' Speech skill tree. You could ignore these things if you want, and if you do it you don't get a super powerful piece of gear, but you do get a fun reward. Maybe if you help enough folks, the neighborhood decorates itself with your colors, balloons, banners, etc? Like Kent Town from the Truth storyline. Maybe vendors in that area give you a steep discount, and that's your reward? Maybe if you do this in each borough you end up with the entire city decorated, and a parade in your honor that wanders around the city?
Granted this would only really work for a sandbox game where you can wander around and waste some time exploring.