Did the prequels really make more money if you take inflation and the change in money from one era to the next into account? They certainly had a lot less cultural impact. The originals were a massive presence in the film years. The Phantom menace was a big cultural event because of the expectation created by years of waiting for something to follow the OT (in other words it was big because of the OT), but the other prequels were just big blockbusters like any other. They weren't this huge event that the old films were in their time.

As an aside, I looked up books about Lucas on Amazon. There were a good dose of Lucas books coming out in 97 through 2001 (from circa the SE to after TPM and before AOTC) and then it drops off. The only book of significance in more recent years was the 2005 The Cinema of George Lucas, which seems to be a big coffee table luxury book that doesn't have a huge amount of depth. But it seems to me that there's been no biographies in recent years and no studies of his films in general (ones with his name in the title, anyway) other than that one big coffee table book. It's like he got a lot of attention when he got back into action with the SE and TPM and then it dropped off. Did people give up on reading about him after AOTC was so bad? I mean, I know that for me AOTC was the turning point. I was way too tolerant of the SE back in the old days and while TPM was a disappointment it had its good points, but AOTC had no merits whatosever and was for me the sign that told me Star Wars was fucked (though I should have figured that out in 97 with Han shooting second and Roger Rabbit Jabba).