From the early days of superheroes, one common element among them has been the secret identity. It should go without saying that if a person is going to go out and fight crazed supervillains, having a secret identity and a private life is a crucial element.
Not all superheroes have a secret identity. Some heroes don't have the choice of having one as they're identity becomes known for one reason or another. There are pros and cons to having and maintaining one.
Despite some of the obvious dangers of allowing the entire world to know who they are, there are still those heroes that continue to put themselves out in the public and continue their fight against crime. Juggling a dual life isn't easy but maintaining the secret could be one of the most important missions in a superheroes life.== TEASER ==
A superhero without a secret identity would be equivalent to a celebrity in the real world. We see them in the tabloids all the time. They can't go to the grocery store for a quart of milk without photographers harassing them. Superheroes without a secret identity would have photographers to think about as well as supervillains with a vendetta for revenge. There are villains that will strike at the weakest point. A superhero without a secret identity can't really have any hopes of a private life. Friends and family would always be in danger. This might be the deciding factor but there are other reasons they might not have actually considered.
It's a surprise Mister Fantastic and the Invisible Woman's children haven't been put more at risk. These poor children are pretty much stuck staying in the Baxter Building all the time. They can't simply head down to the local playground. Who would want them over for a playdate knowing the Mole Man or Annihilus could attack and destroy their home at any moment?
Another issue with having kids is their safety. Reed and Sue have been pretty good parents and the Baxter Building has the most advanced security system but how many times has it been attacked? The entire building has been sent into space...twice. Social Services even paid them a visit and threatened to take away Franklin and Valeria.
What about any sort of insurance? A hero with a public identity will have a hard time getting life, medical or even car insurance. They would have to pay super-high premiums in order to be insured. If the world knows who they are, they would always be a target and that means their lives and possessions would be at risk as well.
Without a secret identity, everyone is going to expect the hero to save the day. If something goes wrong, they'll blame the hero for not doing their 'duty.' If a crime occurred in their neighborhood and the hero happened to be busy washing their hair or mowing their lawn and failed to stop the crime, they could probably expect some hatemail or flaming bags of poo on their doorstep.
Then again, would they be able to be a home owner? Who doesn't enjoy a nice barbecue in the backyard? If they were part of a team like the Avengers that has their own mansion or headquarters, they could just hang out there. But they wouldn't really get any privacy unless the only friends they had were other members of the team.
All of this might seem like common sense but there are still heroes that refuse to even try to have a secret identity. It could be that they enjoy the thrill or attention of everyone knowing how powerful they are.
A hero that is invulnerable needn't worry about their own safety while going out to the movies. Even if the heroes don't have any non-powered friends or family to worry about, they're going to want to have a secret identity to get some peace once in a while.
It could be argued that in a city full of millions, they wouldn't always be recognized but today's celebrities know this isn't always the easiest thing to do.
A secret identity is for more than just protecting friends and family. Superheroes need to understand the importance of this.