Because anyone can get those high end PvE pieces, not everyone can get the high end PvP ones.
Even if it’s one or two pieces, it shouldn’t be in the game.
The current system is perfect, honor gear is easy to get and 2400 viable while conquest gear helps beef you up along the way and tier becomes BiS eventually for certain specs.
There’s no need to overcomplicate for the sake of reviving a bracket that no one really cares about anymore.