>But they didn't actually build WoW classic. They just built another version of the game. Gameplay wise it is drastically different.

what?

i played vanilla in 2004, and i played classic when it released. your description is extremely inaccurate.

Explain. Classic is nigh identical to the old version in all the ways that matter, primarily gameplay, with fairly minor improvements.

Drastically? What are you talking about?

You can start here: https://www.youtube.com/watch?v=iKF9OcncX54

According to Blizzard, they don't even have access to the original source code. Instead starting from some version they happened to be able to recover.

When you say "nigh identical to the old version in all the ways that matter", what you are saying is that the game is identical in the ways that matter to you. Some of us actually value the original 1.0 experience. Just for example, the original WoW never had server transfers or "layers" in the game.