Do you know what a “video game” is? People will play what they want, when they want and how they want. After last Classic phase there was nothing new aside of TBC and it’s obvious people will play new instead of staying and doing pointless Naxx runs. And people WANT WoTLK - either those that will join only for WoTLK or those that are progressing TBC now. Some will stay on TBC but very little.
And on private server people left their Naxx fully geared toons to just level FRESH on new realm - over and over again. If you expected “endless vanilla” or some “magical MMORPG” then you did your research very poorly.
Nobody cares by now, often having multiple TF in guild, multiple scarab lords and so on.
New players don’t come to dead realms, they come for fresh. And they will spellcleave to 60 and start farming MC before you even notice.
You don’t have to, but other made the choice to do so. Some play FRESH while some other play Solitaire.
It’s 2021, you won’t be showing the raids. Sorry but players will optimize the fun out of any game and Classic in 2021 is completely different game than 18 years ago. People know what they will do day 200 before they even start playing.