Yeah, I was really, really uncomfortable with the "natives" for a variety of reasons. I noticed that the filmmakers also killed off all the people of color on the crew of the pearl, after implying that they were kind of sneaky. I almost walked out at that point - I was feeling icky.
It's wierd, because it seems that they tried to reflect historical reality in that they portrayed pirates of different cultural and ethnic backgrounds, but could only handle the diversity in a typical Disney way - all the accents belong to the villians or clowns, etc. It's frustruating, because I want to be able to just sit back and admire Johnny Depp, and instead there's all this unsettling crap, which, as you point out, is not very suprising, but disappointing nonetheless.
I loved the Swamp Witch, though. Ahh, the ambivalence . . .