Hmm, in all seriousness, based upon George Lucas' #1 concern since the box-office results of Empire, he probably didn't like the script because it was too sophisticated. Most notably when it comes to Indiana Jones, he prefers simple stories that keep the action moving and don't bother with anything else.
But, that's coming from someone who's not a huge fan of the series or even Raiders. I like all of the Indiana Jones movies, since they're incredibly fun to watch, but they have nothing deeper for my mind to latch onto and that's what I usually return to movies for.