Even David Warner's St. John Talbut in STAR TREK 5 was more substantial and interesting than Professor Harold Oxley was in Indy 4. What a waste of someone of John Hurt's callibur. Just sit around and do nothing, or act Mentally Challenged in a Helen Keller kind of way. And the reason why his backstory is so interesting is actually because of RAIDERS ...
Oxley was a friend of Marion Ravenwood's father. He's a friend of the family who refused to have anything to do with Henry Jones, Jr., because of how he treated her. Whatever potential information was there, all of the Human Drama that would've added some interest to Oxley, for us to even care about him, in the first place ... all of that went bye-bye in favour of having John Hurt play The Village Idiot. And worst of all with that, it never had to be.
The expression of the Crystal Skull's effects could've been demonstrated through other means, or other people. Just to have Oxley confront Indy and get some of these past issues dealt with would've done so much, within the existing script, to just give the story some passion. And let Hurt shine, somewhat ... anyway, that's all ... that's nothing. This movie doesn't want to deal with anything profound. Even Mutt's true father is revealed in the most light-hearted manner possible.
In any event, the joke is that John Hurt demanded he be allowed to read the script first, before being cast for the role, which - apparently - Spielberg always had him in mind for (!!!). So he's sitting at home, with the guy who delivered it waiting on him, reading all this and after ALL of the lameness that this chore revealed, he goes ahead and accepts the part, anyway. Personally, I suspect this story of his is made up, because there's only one reason to have taken the part and that's a paycheque. The character and the story he's imbedded in are shite.