"They are just images placed randomly together"

This is a false statement.

Neil Cohn, comic theorist, was so intrigued by comics that he decided to write his undergraduate honors thesis regarding this subject.

According to Cohn,

Most people believe that the reading of comic pages moves along the same order as text: the "z-path" of left-to-right and down. However, what happens when layouts are more complicated than simple grids? This paper reports the findings of a psychology experiment which found that readers follow a far more complex process of page layout navigation than the z-path.
http://www.webcomicsnation.com/NeilCohn/theory/series.php

Comics not only interest your 8 year-old cousin, you know?

Graphic Art always has a purpose. It might seem like it is a convoluted mess, but it's work of a genius. Check out Navigating Comics and read what Cohn has to say about the highly structural method of formatting comics. If you don't believe comics are an art medium, you will after you read Cohn's essay.