This is a fascinating story for reasons that have nothing to do with the Spanish or Aztecs. This is a story about technology and the internet; also it's about how history cycles.
The Spanish were probably a poor reporter of the conditions they encountered. Even if they had tried to be completely objective, they would have had a very difficult time explaining what they saw without a lot of context they didn't have. I think most people know this instinctively.
History moves in cycles, with one bunch being praised by one generation only to have them reviled by the following one. Then it will swing back the other way. Astute authors and historians can make some cash by riding the wave when it appears. After hearing such a one-sided story for so long, people are ready to hear the other side. It seems like it is an important thing that needs telling.
What does this have to do with the net? Take a look at the comments. You're the only person that read the first-hand account. Everybody else is riffing off how "right" the story feels, then projecting various present-day political and emotional responses to an event from 500 years ago.
Don't get me wrong, I think that's a great thing....as long as students stay tuned for the next flip around. Then they start realizing that for any one set of events, hundreds or thousands of narratives are possible. That's not a weakness of history, that's its strength. History is not a science where there is only one right and wrong. It's a humanities subject where the more we study, the more we understand about ourselves.
I'm not sure how this works in the age of Wikipedia where so many people want to Google for the right result. Sure is fascinating to watch, though.