I might be wrong that leveling is perceived by the majority as "work" and not a engaging and a genuine "fun" experience all the way.
Some people already posted here saying they enjoy leveling immensely, so i dont know.
I fail to see how though, specially for a new player.
Thats an awesome way to make people "want to make a new character"
Something like this i think would be amazing for WoW.
The idea of making leveling just as fun as endgame...would benefit WoW immensely imo.
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Asking a "new player" to "stick with our game" and "work for up to 1 month without having fun" for a "mystery box endgame" you may or may not enjoy...
I think this is too much to ask for a new player.
Ofcourse they are gonna quit.