Yeah that squealing MOUSE droid running away fast after Chewbacca growls at it was more sophisticated than the childish slapstick and toilet humour we saw in the PT and ROTJ.

In what way? Admitedly TPM was overkill, but I don't see why ROTJ gets such a bad rap: it balances the darkness of the Emperor scenes with the lighthearted forest battles with the Ewoks. Remember that in ANH the main characters don't take their mortal danger very seriously, and the Storm Troopers have never been able to shoot anything except Uncle Lars and Aunt Beru, even when our heros are right in front of them and not even moving (Luke after Obi Wan dies). To be honest I think TESB is the anomoly here. Anyway, these movies aren't meant to be overly serious but instead a timeless mythology with special effects and child-like humour.