Good point. Though it does bear repeating that Mayas didn’t have the monopoly on ritual human sacrifice; it was a tradition spread throughout pre-Columbian Meso- and South American cultures (as well as elsewhere in the world). Much of what we know about this practice, however, is from the Spanish conquistadores and priests recounting what they saw — and necessarily they’d have certain biases and interpretations, not always for the positive.
For example: You’ve probably heard the Quetzacoatl legend about how the Aztecs believed their feathered serpent god would one day return to their shores, with pale skin and hair, to reclaim Teotihuacan in his name, and that’s why Monteczuma II didn’t fight back against Hernan Cortes’s invasion?
Well, not only is that a wildly inaccurate portrayal of the events leading up to the Conquest, but the primary source most often referred to on the Quetzacoatl legend was one of Cortes’s priests, who heard the local legend and transcribed it for posterity—almost certainly changing it as needed to make it seem like the Spanish conquest was inevitable. And hey, maybe he succeeded, because many people who hear the story these days accept his version without question, marvelling about how those darned Aztecs must have had magic powers of prophecy or whatever, to know so much about their coming downfall. (Barf.)
Moral of the story: Always question the source of a legend — an idea that applies just as well to Dragon Age as it does to Nahua oral traditions.
Okay, so that was more of a tangent than anything else. Woops. :)
As for your other question, I try to use the terms the native peoples themselves use whenever possible and I’m sure I’ll be understood. I’ve heard firsthand ethnic Maya refer to themselves as both “Mayas” or “Maya”—as long as you don’t say “Mayans” I think you’re safe—but I admit I can be as sloppy in naming terminology as the next person when I’m typing fast for the Internet. I’ll try to be more consistent in the future.
Still, these aren’t English words, and so I think it’s tough to argue that it’s patronizing when people don’t pluralize these words according to English standards of grammar. As far as I understand it, linguists are mixed on exactly what the proper pluralization should be, but ultimately, many of these names aren’t even what the peoples in question originally called themselves (consider Aztec vs. Mixtec, for example).