The one frame they showed from the Lion King really stood out. The difference in how the background animals were washed out by the sunlight makes the film version look significantly better.
In the lion king example you weren't meant to see all of the detail the artists drew. In the Army men example the color on the digital version is nothing like the color of the actual toys.
They originally made those movies the way they did intentionally because what they wanted wasn't crystal clear images with unrealistic colors, they wanted atmosphere and for things to look realistic.
Film grain and dust can be excessive and distracting. It's a good thing when artifacts added due to dirt/age gets cleaned up for transfers so we can have clear images, but the result of that clean up should still show what the artists originally intended and that's where disney's digital versions really miss the mark.
That's the point in that Lion King frame, though. They drew it planning for it to get washed out by the sunlight effect, and when it's not it absolutely ruins the "vast crowd" effect they were going for because you can clearly see there's no more animals in the background and it's just 20 guys standing there.