think this way, a lot of people saw the original three movies first as a kid and so they have always carried that initial viewing in their minds. but when they saw number 4 they saw it as adults. and i bet it didn't even cross their minds to watch it with the same mindset as that of their childhood screenings.
a friend of mine, who shall remain nameless, wrote a negative response to good ole indy 4. included in this response he said:
Okay, okay, I know - Indiana Jones is an action movie...But the latest movie? What did we get?
Aliens. Monkeys. Big ants. Refrigerators in nuclear blasts.
let us pick apart a few of the more, let's say, unrealistic parts of the first three indy movies, shall we?*raiders of the lost ark*
-giant snake pit
-giant rolling boulder
-marion ravenwood's accent
-THE ARK OF THE effing COVENANT
-the effects of opening the ark
*temple of doom*
-short round (nuff said)
-willie scott whining "indeeeee" continuously throughout the movie
-the bugs
-the ENTIRE concept of the movie (the family guy spoof is spot on with michael eisner btw)
-eating monkey brains
*last crusade*
-the snake in the train
-infiltrating into nazi germany and coming face-to-face with adolf hitler
-the rug on fire/hearth scene
-THE HOLY effing GRAIL
-the melting face/body
i hope this shows that aliens, monkeys, ants, and nuclear explosions aren't too far-fetched in the story of indiana jones. in fact, they're thematically right on target. what's that formula again?
supernatural/extraterrestrial/religious artifact + gross animal scene or scenes + impossible situations + interesting sidekick (a bit of a stretch with short round) + love affair + frightening global power figure = indiana jones movie
i rest my case.

