My argument with the op’s points are that it didnt fall in line with how TBC was when it was released. This is meant to be a museum piece, trying to bring the same experience to the players. Most likely they will allow people to either copy or transfer to the new TBC servers and they collapse a bunch of the classic vanilla servers together and keep the vanilla ones stagnant. For people leveling Shamans on alliance or Paladins for horde they had to level from level 1 as this was the norm for TBC. That allowed people to start new characters to level with their friends. Being 100% fresh isnt in the spirit of an “Expansion” as you are expanding on what you already have not a new game with different content.
Reasoning for fresh everyone at level 1 would be so the new classes for the factions dont have to level in quests so they can spam dungeons with mages and warriors that are now releveling. Plus when TBC was out alot of tanks still used Thunderfury (as well as some T3 set bonuses where used in tbc raid) and this was the normal when I first hit 70 on TBC release.