I feel the same way about that. Indy 4 took no more suspension of disbelief than the other 3 movies. In fact, for me it may have required less than for Temple of Doom and Last Crusade. Don't know if I've mellowed with the years, maybe that's it or maybe not. The point of all the old movies, serials and matinees of the 30's and 50's, the ones that Lucas and Spielberg used for inspiration, weren't really about realism, you know. They were all about totally fantastic stuff. Little kids like Lucas and Spielberg loved it. Based exclusively on anecdotal evidence, I think it's possible that many people today aren't willing to exercise the same suspension of disbelief with many movies than people the same age would have 50 years ago. It's just a theory, mind you.