The way the powers change their attitude is worth watching/reading. And to top all of this, even with that nerdy attitude they date the hottest girl in college or the office. They set a precedent that "geek is not bad."
They can induce glory even from the smallest thing. This forms an interesting story behind their powers, and people love it. Another reason for loving superheroes is their positive attitude. The audience is impressed with the way they face the bad times and fight it out.
Girls almost blush when they see the handsome face behind the mask, and boys root for the strong personality. The characters are awe-inspiring and they are carried very well.
They understand the plans of their enemies well in advance and always have a solution for it. Even if the situation turns worse, they find a way to come overcome it. Be it a strong enemy or the angry girlfriend, they know best how to fix both.
They know what's good and what's bad, and they don't ever make a wrong move. They stand for what they believe in, and it's always the correct path. Their virtuous approach impresses the audience and makes them fall in love with their powers.
They are the center of attention of the whole superhero series. The color, the design, and exceptional weapons are stunning. Superhero costumes form a part of their identity.
A symbol is a superhero's ID card. The symbols are simple but attractive. People are such big fanatics of their symbols that they use them in key rings, tattoo designs, T-shirts, mobile/desktop wallpapers and what not.
They can ridicule anything, including their enemy's best moves. With their wit, they keep on entertaining their fans, and this is why they are loved so much. Not many people like to be serious, and thus, they don't make it serious.
They are willing to sacrifice everything to save people. They are the soldiers in fancy costumes who have vowed to save the lives of people at any cost. People fall for their attitude and determination.
They even encourage geeks by proving that they can also get the hottest girls. People know they are just fictitious characters, but they show how to follow the path of virtue. Though they have supernatural powers but then people start believing that you don't need to have such powers to be a hero.