You are describing it, as if that is a problem? 
No, a campaign is so so much more than a story.
Since you are so stuck on the story stuff, lets rip the story out of the campaign+. Would that help you move on?
Indeed. And campaign+ would fit greatly as one of those other end-game things.
Since doing the endgame activities are not exclusive to one another, it would not particularly matter what the other activities are.
No it is not, at all. It is just better game design to make better end-game, and when you can make better endgame at very little extra development cost, it is an obviously good thing to do.
I think that is what everyone expect. I would hope key dungeons take a bit longer though. Like 15-30 minutes. Due to slowed down combat and movement. Also, no timer!
Hopefully now.
How they scale is quite irrelevant for this thread however.
And they would not have to! Seriously.
But for some players, it would be amazing.
Some video games surely believe they are moves 
Nobody, and certainly not I, are trying to stop you from doing that.
Not even a little.
Exactly! You are getting so close to understanding. 
Hence, it does not matter how keyed dungeons are scaling, campaign+ simply need to scale the same way.
That is clearly not true. Plenty of games offer no difficulty whatsoever. Often because they are not trying to. And sometimes because they failed in their attempt.
Please lord no.
PvP should offer basically no gear rewards. It is a place to fight other players. That should be its own reward, and nothing more.
Plus of course cosmetics and all that stuff.
Definitely. Itemization is one of the most important pillars of an A-RPG, along with character building, and combat.
End-game is pretty importa too though. But this only makes campaign+ an even better choice, since it allows you to have end-game at very low development cost.
I mean, in this imaginary scenario where end-game and itemization was competing for development resources, then it is key dungeons that should be removed, not campaign+
Yep. Stop scaling rewards much earlier than you stop scale the difficulty.
Like if there are 10 difficulty levels in end-game, stop increasing droprates at difficulty 7.
Well, speaking of important pillars. Release date is far down the list. Give me good itemization, character building, and endgame before a release date. Even if it pushes that date back years.