It can't be easy being Clark Kent.
It's very easy being Superman. Everyone knows he is an alien, possesses the powers of flight, super-strength, and super-speed, laughs at bullets, and sees through walls. And he doesn't wear a mask, so everyone assumes he has nothing to hide. Superman can do whatever amazing things he wants, and no one is surprised.
However, when Superman arrived on Earth, he was not quite ready to reveal himself to the world. He assumed the alias of Clark Kent, mild-mannered reporter, so he could walk among its citizens unnoticed. Meanwhile, as an employee of a major metropolitan newspaper, he can observe the citizens of his new planet, know when his aid is needed, and has an excuse to get close to the action.
This occasionally—well, pretty frequently, actually—leaves Superman on the horns of a dilemma, or even a trilemma. Danger strikes, and Clark is faced with three options. One, he can dive into a nearby storeroom or phone booth, transform into Superman, and do what he does so well. However, he risks exposure. In the early 1940s, Superman is still a mystery man by choice. Two, he can remain in the guise of Clark Kent, meek everyman, and do nothing. This preserves his secret, and no one really expects better of Clark. Unfortunately, it's also out of character for someone who has "sworn to devote his existence on Earth to helping those in need," if he ignores those in need because it's inconvenient.
Option three—the one we hear so very often in radio's Adventures of Superman—is to take action as Clark Kent.