I want to bring this up as we’re approaching Wrath of the Lich King - Classic, which will bring controversial additions to the game. Later on, we could enter Cataclysm which brings with it its own changes. In general, the game starts to adapt to the player, instead of having the players adapt to the game. This has been cited as a major reason for why players left the game in its later iterations.
Pristine Realms, as mentioned by Blizzard around 2016, were supposed to be realms where a lot of features added to the game over the years would be removed. We would be left with a game similar to Vanilla, except that we would have the new class abilities, class balance, combat, world continents, raids etc. from the newer expansions. Examples of features that would NOT be in the game (and this is open to discussion!) would be :
*Cash Shop
*Flying - instead we could have faster ground mounts (portals/Flight Paths could be added to otherwise inaccessible areas)
*LFD (automated Dungeon Finder) - instead we can use the LFG tool from retail
*LFR
*Cross Realm-Zones
*Heirlooms - instead we could have EXP-boost weekends, events or simply reduce the EXP needed to level
*Pruning - the removal of RPG-elements and the eventual dumbing down of the talent trees
*The lowering of the difficulty level for Heroic dungeons (in WotLK Heroic dungeons evolves into speedrunning with AoE - instead they could be kept hard, thus requiring teamwork and strategy)
*The removal of Elite/Group quests
*The nerfing of mobs in the open world (which leads to the world no longer feeling dangerous to be in)
*Borrowed power and excessive ‘systems’
Obviously, there are a lot of disagreements about which of these features were actually good for the game and which turned out to ultimately make the game worse (such as making it less rewarding and/or social due to excessive QoL-features and accessibility). Perhaps there should be polls and player voting, like in Old School Runescape, to gauge which ones to keep and which ones to remove?
Ultimately, I believe Pristine Realms (just one or two!) could be profitable for Blizzard as it caters to an even wider audience - now players can choose between Retail (with its QoL-features), Seasons of Mastery, Classic (with its changes) and Pristine WoW. Instead of players quitting due to changes they don’t like (like the cash shop, LFD etc.), they can play Pristine WoW instead. As for the concern about a divided player base, I suggest Blizzard attempt to merge the lower pop servers together so that everyone, regardless of server, feel like they’re part of a populated game.
But when you look what OP posted its pretty much shows that wotlk itself is already retail thingy