And even changing characters somewhat but still having a development or purpose is arguably fine - it's the changes that aren't good in the context of the movie that are most baffling, especially considering the dedication shown in other areas of the films.
This is as silly as suggesting that Tolkien's work somehow tarnishes or damages nordic/germanic mythology. utterly ridiculous.
Strong feelings for an adaptation or a sequel can taint or enhance how someone feels about the source material even if the original was experienced first. For example, it's understandable if someone who really loved star wars before the prequels and disney acquisition found that they can't help but experience a sense of loss and disappointment while revisiting those original films knowing about midi-chlorians and how the franchise ended up.
The original works are unchanged, but in many cases the way we view and experience them isn't.