How do yall not like The Original Star Wars Trilogy. Thats like the holy grail of Epic movies.
Oh, and the Prequels brought the OT down just by association. 
You have a point there. But kevin smith fans aside, the movie trilogy is pretty damn good film adaption of the Hero's Journey. I read Joseph Cambell's "A Hero with a Thousand faces" its about hero stories all around the world and what they share in common. Lucas did an amazing job of creating a completely new universe with such epic characters and stories.
I think Lucas has always overstated the influence of Campbell's work. He noticed his story fit the form and started talking Campbell up, possibly to butter up critics. If you read the early concepts and scripts for Star Wars (note: Only referring to the original movie because that's the most Campbellian of them), you'll see that most of the Campbellian bits are things he cribbed from Kurosawa flicks. He wasn't DIRECTLY influenced by Campbell - he told a good story, and noticed that classically good stories have similar forms.
Even during the earliest stages of creating Star Wars he actually took his drafts to Cambell, asking him in essense "is this right?".
Am I the only person who watched the Star Wars documentaries? Damn 
Did he say this or does he have it documented somehow? Because he's also gone on record saying some of the unused bits from THX1138 were recycled for Star Wars, which would shade doubt on his claims that Star Wars is a Campbellian masterpiece. If he knew the archetypes and templates so well, why did he resort to using nearly 10 year old material in the movie rather than making new stuff?
It sounds too me like you're overcomplicating the subject far more than it needs to be. Has Lucas ever said Star Wars is a "Campbellian masterpiece"? What bits of THX were recycled? And if bits were, does it really matter at all? Lucas wanted to do a lot of things with his student film which he either couldn't get around to or simply wasn't able to do at the time. Why is it so hard to fathom that *gasp* he'd put some of these things in one of his latter movies?
I don't think so. I think he began referring to Star Wars as Campbellian so he could get some crit cred, no overcomplication needed.
As for THX leftovers - the garbage pit. That's all I remember offhand, and I don't have access to either movie, nor any reading material at the moment.
Fact is, Campbell had a tendency to very broadly define archetypes and any number of zillions of movies could claim to be influenced by his work. Lucas just said his was influenced by Campbell during a period when Campbell was critically popular.
The fact remains that Lucas went to Cambell and sincerely asked him how he could make his movie better; I fail to see how anyone could fault him for that, unless of course they have some anti-Lucas agenda. Cambell's work is in no way original considering he just diagnosed an already existing phenomena. And as I said, Cambell once declared Lucas to be his best student.
Garbage pit? Big whoop. That scene in no way relates to Cambell's book or hero theory/history, so why you bring it up is beyond me. The entire movie is not some Cambell rip off - the archetypes, from the wise old man to the young warrior, go even further than Cambell's work. Lucas' admittance of working with Cambell is in now way a sign of him "cashing in" on Cambell. Why would he have to do that when he'd already "cashed in" in every way imaginable with Star Wars lol?
Before Lucas created Star Wars he researched Cambell's work, as well as mythical stories from all countries; the basic look of Darth Vader is based off Japanese samauri, for instance. He wanted to create a more modern take on these ancient myths, and he succeeded in every way imaginable. Star Wars is popular in every corner of the world, in part because it taps into so many different cultures one way or another. And, as Cambell's (and other people's) work suggests, all myth can be connected by very basic ideas/events.