Good point. Although, I think it has different implications when you think about Peter Pettigrew willingly became a rat to hide and was in the care of an innocent boy. The way they set up Nagini, she's obviously had a fukked up life and will transform into a snake because of some degenerative condition. Then there's the whole racial thing. I don't know. It's kinda messed up. Plus, I'm just kinda tired of JKR making up new shyt about old stuff she wrote, whether it fits or not.
See that's the dilemma with diversity; do you cast lily white actors and they take all the parts or do you diversify the cast and risk casting choices that have unfortunate implications? On the surface there's nothing wrong with Nagini but if you add modern social elements into the mix it is problematic, which is why I don't know if we should do that when it comes to a fantasy series.