This Speech Is Cheesy And That's Okay
When I first saw this scene in the theater, I thought the speech was kinda cheesy, because he's saying the theme of the movie out loud. At the time I thought, well Superman is just tired of Lex's crap, and he's just telling him what he really thinks, so the movie can get away with it.
But thinking about it recently, I realized that this whole movie is about being cheesy and not being ashamed of it. We see it with this scene, Superman having his trunks back, all of the whacky comic book characters and concepts, and the message that loving everyone and thinking everything is beautiful, unironically, is "the real punk rock."
This movie is really a breath of fresh air when so many superhero movies feel the need to make self-aware jokes about their sillier aspects, or make everything dark and gritty. It just plays Superman straight, and delivers its themes sincerely.
"I listen to the music with no fear
You can do it too if you're sincere"