I think what gets to me is that when you read the comments the artist desperately tries to backpedal one minute by going "no no you misunderstand I'm not saying we throw in random token minorities into a classic, I'm just trying to shed light onto other classic fantasy novels that are being overlooked and think LOTR could use more variety is all!" and then the very next line it's "Let's make all the elves from Africa, the wizards from Japan, and all the humans hail from a culture that developed in complete isolation in the middle of the ocean thousands of miles away from anything resembling Europe"
I guess that's kinda what gets to me when it comes to SJWs attempting to tackle: they end up proving that they really have no respect for the cultures they portray just because of how they act like those cultures developed out of happenstance rather than because of environmental circumstances. You know why everyone in the LOTR stories are almost uniformly European? Because the characters are walking in a straight fucking line in a distance that's roughly the same length of traveling from one end of Europe to the other. SJWs can deny it all they want, but if you were to travel on foot down the middle of Europe in the middle ages, the local people would be about the same with only various regional flavors between them. A Polynesian culture that relies mostly on a tropical island climate just wouldn't develop in a European setting because the weather and terrain wouldn't allow for it, nor would most of the other cultures depicted, and trying to work them in would require so many detours and such different world-building that it basically wouldn't be LOTR anymore, so you might as well just make your own fantasy by that point.