This is nothing new. Even back in the day, the only people playing in certain old zones were people leveling... the goal of the game (for anyone other than the insane loremasters) is to get to max level as quickly as possible so you can raid and PVP.
Blizzard is taking steps to allow people to see old dungeons, but they have not yet created incentives to keep people exploring old content. Arguably, it's not a great idea to spread people out... as the game population dwindles it's better to keep the players in the same zones so they feel like they are in a populated world and not a single-player game.
Anyway agree there are some really cool parts of the game that ANYONE could see... but they get abandoned. I care more about old dungeons and old raids, but really they've done a good job of allowing players to see that content and farm it for transmog gear and nostalgia.
Blizzard is taking steps to allow people to see old dungeons, but they have not yet created incentives to keep people exploring old content. Arguably, it's not a great idea to spread people out... as the game population dwindles it's better to keep the players in the same zones so they feel like they are in a populated world and not a single-player game.
Anyway agree there are some really cool parts of the game that ANYONE could see... but they get abandoned. I care more about old dungeons and old raids, but really they've done a good job of allowing players to see that content and farm it for transmog gear and nostalgia.