For example: Peanuts is well drawn, in that Schulz uses his cartoon language in a very deliberate and meaningful way. It didn't just come out that way because he couldn't draw a guy with a normal-sized head. He's able to communicate on an emotional level with the simplest of symbols, and make every dot and squiggle count. This is why looking at the individual drawings doesn't give you a sense of what he's achieved. If you've never seen Charlie Brown before, a single drawing of Charlie Brown doesn't have much emotional content. But over the course of the strip, Charlie Brown becomes undeniably Charlie Brown. There's no separating the drawing from his personality in your mind, and the transmission of the information is instant.
Superman is less effective, because of all the various interpretations of the character, but still, that distinctive costume and it's associations also have some instant emotional content, but it's less specific than Charlie Brown. Charlie Brown is like a letter in an very specific alphabet. Even more so than a written word. As you read the strip, you learn the language of Charlie Brown, and the more you read the strip the more that language is enriched for you. The drawing itself begins to carry more meaning as you read the story over time. Not just the characters, but the sofas, and footballs and birdhouses. While traditional language can become enriched by your understanding of it over time, no symbol or character outside of cartooning can contain that kind of history and richness on its own. Pictographic language like ancient Egyptian hieroglyphics can, but that, in its way, is comics! Really, any book that can't be read and understood without the pictures is essentially comics, which includes many kinds of picture books. Even drawn instructions in instruction manuals use the same principal.
So that's one of the reasons that comics are completely and totally awesome! Comics as a language has enriched my understanding of language in general. And the universality of the language is also pretty fascinating. Someone from an Asian country can make a wordless comic that, aside from very specific cultural references, I can essentially understand There's no other language like that in the world. But pictures in general are still cultural and have different cultural significance in themselves, and aboriginal cultures not exposed to these kind of pictures might not be able to interpret them.
Also different cultures have different pictorial histories, so just the shape of a Schulz football and how the marks are made, aside from its footballness, are a reference to our culture because of the way we make marks, and the history behind how we make those marks. Take another culture's specific pictorial vocabulary and its origins, say, Japanese woodblock printing and Kanji, that give Japanese comics their own vocabulary that is uniquely understood in a different way by Japanese than by us because of the style of mark making itself and how Japanese people are immersed in their own culture from birth. But you still have some universal symbols, like the way babies can understand a smiley face, that I imagine even aboriginal cultures would get.
This is why I'm completely and totally fascinated by the medium and find it hard to understand why everyone isn't! It's why I'm attracted to even the crappiest comics (aside from the fact that I just like superheroes and rocket ships), because there's always something to discover in how the artist uses symbols, because an artist can't help but draw in their own unique symbol vocabulary.