This is something that people really need to start to understand, not just for Classic or WoW but software developement in general. Fixing a bug isn't just flipping a switch or changing a single digit. You have a machine with literally hundreds of thousands of parts, designed by dozens of different people at different times over the course of 20 and more years. You change a single thing and it might break 50 other things in very subtle ways that might not even emerge until months later (i.e. the very high M+ keys some players got at the start of BfA).
Things like Tauren melee reach being bigger, which is something I experienced going away live during Black Temple Illidan progression (at least for that particular encounter), is confusing to players as it's a significant advantage over other races in some instances. No quest tracking is another apparently confusing issue, as many Mankirk's WIfe seekers well know, and there's a whole lot more where that came from:
If you’re eager to claim your character name in WoW Classic, take note: we’ll be opening character creation on Tuesday, August 13.** Players with an active subscription or game time on their account will be able to create up to three characters per World of Warcraft account. We’ll have more information on realm names closer to launch, but rest assured—you’ll have plenty of time to figure out your plans for realm domination!
The system is automated, meaning that once slots are available, beta testers will be chosen, without any beta key to speak of. Kaivax then goes to stress the importance of your account security, stating that, “any third-party e-mail messages, websites, or in-game whispers that offer beta keys or access to the WoW Classic Beta should be considered illegitimate and ignored or reported.”