Temple of Doom was really disturbing in several places. Spielberg and Lucas both admitted as much, given that they made it during some dark times in their lives.
Kingdom of the Crystal Skull was just unnecessary. Not to mention Indy escaping a nuke blast in a fridge, and Shia LeBeouf.
Anything Goes?
Couldn't resist
I can tollerate Temple of Doom, but Crystal Skull doesn't even register that much. I have watched the first three several times in the last four years, but I can't remember watching Crystral Skull save maybe once in that time.
Part of the problem is that Spielberg doesn't like to do the same thing twice and in the quest to find something new with a new approach to the series, he ended up going too alien (litteraly and figuratively) for most Indy fans.
