I am of the opinion that : what is done is done.
I am not a fan of whole sale retcons unless it is adding something - like the Draenei being retconned added to the universe. I would not be a fan of just cutting out the lore we have experienced. There would have to be a VERY good reason - like renaming things named after the Cosby Crew or other bad actors. So far, the only reasons I see are a matter of taste.
I can’t sit and defend every plot point in Shadowlands as some great work of fiction. That does not mean it should be retconned out.
I agree it can make alot of more spiritual cultures seem as though they are wrong - but there are tons of afterlives we do not see. We are basically dealing with the covenants that run the place, there are other realms of death. I do not see it as so egregious, if you consider the background afterlives we do not see.
I delight in the lamentations of Arthas and Garrosh fans. They seem to be among the most upset about Shadowlands. It definitely puts a smile on my face, the way they cry about how those characters were handled. So, that makes me like Shadowlands even more. I had nothing but contempt for Arthas and Garrosh since I first encountered them. I always thought that the way they were worshipped by some fans was strange.
I could have just enjoyed their fate, but the tears from their fanboys made it extra enjoyable. If I was going to give Shadowlands a 6 out of 10, those fanboy tears add an extra point, and make it a 7.