LogFAQs > #960882558

If it was JUST aliens people would probably handle it a bit better, but it was poorly explained and inconsistent aliens. In the older movies, you KNEW how the arc worked and where it came from and why it was where it was. You KNEW what the stones were and how they worked and why they existed. You KNEW what the holy grail did and where it came from and why it was where it was.

The skulls aren't nearly as fleshed out. Why did the aliens come down? Was it 1 alien that split into parts? If not, why did they merge at the end? If so, why did they split in the first place? Were they just sitting in their circle chamber and one of their heads fell off, causing the others to turn into crystal? Why did they fill their ship with random crap from around the world?

You can do "complete unknown" well (see: Roadside Picnic), but the aliens in Indy 4 suffer from being half-explained. Without the historical context of the mcguffins in the previous films we're left with these big gaps in understanding, but rather than play off that uncertainty it all comes together in a very tangible way that just creates questions rather than mystery.