Steven Spielberg has a interview in the new issue of Empire, and if you hated the idea of aliens in 'Indiana Jones and Kingdom of the Crystal Skull', you're in good company, because he did too.
"...I sympathise with people who didn't like the MacGuffin because I never liked the MacGuffin. George and I had big arguments about the MacGuffin. I didn't want these things to be either aliens or inter-dimensional beings. But I am loyal to my best friend. When he writes a story he believes in - even if I don't believe in it - I'm going to shoot the movie the way George envisaged it. I'll add my own touches, I'll bring my own cast in, I'll shoot the way I want to shoot it, but I will always defer to George as the storyteller of the Indy series. I will never fight him on that."
Aww golly, that's kinda touching. I can't help but admire the way he knowingly screwed the audience by making a terrible movie just because his friend asked him too. It really inspires confidence.
(what sucks is that these two used to be great at this. no, really. here is an outstanding article about the first Indiana Jones story meetings between Spielberg, Lucas, and the great screenwriter Lawrence Kasdan. I have no idea what happened since them but i doubt Lucas could even write a note telling me he went to the store without fucking it up. 'You needed milk and went to Area 51? What, why? That seems unreasonable.' "