Beyond all the technical issues which you are choosing to ignore.
You are putting a wrapper on a classic car.
It isn’t good for the game. Vanilla is amazing as is, what blizzard needs to do it be uncompromising and focus on marketing the good parts of the game.
Instead of tilting and bending to retail players that are already milked to the max.
New players want vanilla not some retail-hybrid-abomination with a mix of textures and styles.
Then take a serious look at the technical things I brought up.
Just because something works in program A doesn’t mean it is trivial to implement in program B.
If they are non-issues to you, I would suggest you to try and implement a tiny version of your ask in the open-source wow. I think that activity will show you how complex of a request this thread is.
Likely far harder to do Era / the fresh servers, because there are people with expectations on Era. Whereas half of cata has been broken from the start, so expectations are very low.
Also Era download is comparably quite small, add a ton of stuff into it and it could easily almost double in size.
On vanilla we notice even the tiniest changes (slight changes in how bosses act, tiny bugs to abilities, etc.)
If you’ve been on these forums for a while, then you know that the argument “It has literally no impact on you” has been applied to every topic ever made here.
All it demonstrates is those people haven’t put much thought into it.
Blizzard had to start faction locking on pvp realms in SoD and now the anniversary servers because the classic community massively faction stacks them otherwise /shrug
Animations and spell effects get changed all the time and never reverted back. Same for both Era and Anniversary. The retail tourists are slowly winning.