What's the reason why the creators of so many comic book heroes (like "Superman" and "Batman") felt compelled to give them CAPES?

Many characters (Spider-Man, Green Lantern, The Flash, Wonder Woman, etc.) didn’t seem to need one, and got along fine without one. Yet. the most famous American icon, Superman, seems to be almost “naked,” without his.

Why do you suppose it seems so natural for him to have one, and what real purpose do you think it serves, other than having a pouch in it, in which to store his Clark Kent clothing?

And yes, I will admit it does indeed look beautiful, to see it flowing behind him in the flying sequences shown in the different TV series and movie incarnations.

But, why does he need to have one? Why does Batman have one?