why do so many (especially older) comics look ugly?

i'm mainly a manga reader (also since it's just easier to find and read both online and in person) but i have still read some comics and watch comic videos (Sir\_Superhero, Nikhil Clayton ect.) and i've noticed that a lot of superhero comics just don't look visually appealing how can a weekly manga made entirely by one guy look so much better then something made by a whole team (also why is so much of it so hard to read? I feel like they don't put much thought into panel flow and page layout) if you have any Marvel or DC comics that look good i'd love to read them