A lot of people in the world hold very strong, completely irrational and baseless opinions, often on very serious real life matters. It's not surprising there's a sect of "anti mtx" players in WoW, too.
When it comes to wow, this is a far bigger issue clearly because of who the players are. Many are oldtimers who are incapable of catching up with modern reality. If you look at other games, cosmetic MTX is almost unanimously accepted and doesn't bother almost anyone.
It helps to realize that these people crying online about a mount or a transmog set are in the extreme minority. Same as with most controversies in WoW. At large, people either buy the cosmetics or not, and carry on with their lives. It's okay to browse the forums from time to time and look at the drama threads, that can be fun, but don't get too invested in it cause it will just annoy the hell out of you in the end. Whenever a new cash shop item hits the game and drama ensues, I like to go to a populated place in the game and just see people enjoying that new piece of content. I can recommend that to everyone - really shows you the difference between forum reality and reality
And yeah, obviously have to agree with OP that people who buy tokens and at the same time shit on the system are pretty silly, but again, what can you do.