While that may be true I defy anyone to watch TPM and not see those ethnic stereotypes.
I think George in his eagerness to evoke all things Buster Crabbe thought he could use them if he transfered them away from the original human model and onto an alien.
Jabba was the sort of fat sultan that Frank Thring used to play, Yoda was the oriental sage and martial arts trainer, the Ewoks were any generic African tribe from a Tarzan movie so George thought he could give us Stepin Fetchit, some shifty trade grabbing Japs and a Semitic child slaver in much the same way.
The world had moved on (even from the 1980s). Sir Alec got into trouble for browning up in A Passage to India where nobody really cared in Lawrence of Arabia. Episodes of Doctor Who are routinely branded racist for using yellow face (ignoring the limited number of oriental actors available to the BBC at the time).
So come 1999 one would hope George would have realised there are some things you just cant get away with anymore. It doesn't stop the depiction of women and ethnic Sikhs in Star Trek Into Darkness as being equally behind the times.