well, they add to the credibility of what's being said. harder to fake.
Actually gives a lot of context for someone not familiar with the topic/data. I learned more from the plots than from the prose.
Reminds me of wtfhappenedin1971, although this is arguably less bad because it at least has some prose
Terrible presentation when the reader has to think "what is the significance of this graphic?" with sooo many of them. But hey, looks impressive at first glance and if this were high school it'd fill the minimum page requirements.