You raise an interesting point here. Is Dinosaur really any less scary than Indiana Jones? Nope. And Indiana Jones had been neglected for so long that the experience was awful up until three months ago, but Disney certainly wouldn't dare remove that ride. I'd even argue the Dinosaur ride experience was equivalent, anyways. Furthermore, Universal is building dinosaur theme attractions to great acclaim, so it's hardly an issue of stale property.
The problem is that there simply aren't enough rides. Kids don't have to see Indiana Jones at Disneyland because there's lots of alternatives, but not so much at Animal Kingdom. I suppose you also run into issues of Disney's "family park" image while Universal is not under the same constraints, but Magic Kingdom has Haunted Mansion and the Snow White ride, so I would simply say it's a ride quantity problem. Point is that Animal Kingdom really should keep Dinosaur, refurbish it, and add more kid-friendly offerings. (They won't.)