Not OT... topic progression
Of course, the saga form of Star Wars helped build more solid character arcs, every main character in goes through some kind of a change during the three movies (Luke - from a whiny country boy to a Jedi Master, Han - from a self-center smuggler to a non-utilitiaristic freedom fighter, Leia - from an annoying little girl to an annoying young lady).
Indy's story arc isn't as solid, most of his character preferences were already set in Raiders, and there was not much room since. Both in Raiders and ToD, Indy first goes after the prize for his own interests, he's not much into saving the world, he just wants the Ark for the museum - guess it's the same for Sankara stones, he wants them in a stall. This doesn't appeal in LC anymore however, since Indy never wanted the Grail, just to find his father.
Besides, I reckon that those new episodes of the SW saga have thrown some people to see how silly Star Wars was to begin with...