Well, it started as a gag manga that people want to be to the new dbz. Saitama himself is an analysis of what makes someone a hero. Saitama would be the first to say that being strong doesnt make you a hero, but a hero should push themselves to be strong. In many ways Saitama is the immutable man. He doesn't change, but the world has to change around him. That's why Genos is juxtaposed against him - in a story told straight Genos would be the perfect edgy underdog hero, and in many ways since Genos is genuinely heroic he can recognize the depth of Saitama that is often overlooked. Genos wants to grasp what Saiatama has, so he follows him. Saitama mighy now grow, but through the story we can pull back his layers, and see how he effects growth amongst his peers.
Another thing One likes to do, as seen in Mob Psycho, is investigate human social relations, especially between being genuine and simple minded, or complex but insincere, and what are your limits to your virtues. One likes simple protagonists with depth. Of course, Mob grows as he establishes his convictions, while Saitama just asserts his own, but they both have trouble "fitting in." Anywho, I'd like to avoid rambling much longer.
tl;dr
>>60730
I think the point is to come off that way, to tell the story better, since that's what most of the characters in the manga themselves think.