That's the problem: it wasn't done very well. Star Wars characters were pretty stock, and I guess IJ were, too.
Dude, I've been watching the Indiana Jones movies all afternoon, and I must say: there isn't anything about them that ISN'T stock, especially when you consider the fact that they're basically rip-offs of the old Adventure films (at least from the clips of those films that I've seen in comparison with Indy.) Star Wars, at least A New Hope, is nearly the same way: hero rescues damsel in distress and combats an evil empire. Been done a million times before and since.
But they actually were done very well, meaning the actors did a great job with them.
Well, sort of. Mark Hamill isn't that great of a live-action actor, and neither is Carrie Fisher. (Harrison Ford is ALWAYS awesome, but Hamill is really at his best as a villainous voice actor.) The best performances really came from the villains. (And Sir Alec Guinness.)
I didn't think any of the performances in Avatar were particularly engaging.
I disagree. I think they did well. I was engaged during the whole movie, and really cared about the characters.