I’ve got 75-80 offline characters, probably 15 odd online characters & a bunch of CT characters. The campaign is wearing a bit thin now. And yes, I prefer the pace of character development/growth during the campaign.
I feel you. To me, the reason is like how the developers wanted to make a game, instead of making a world.
There are many scrapped or half-finished zones, quests, lore, etc., that if they were to finish properly, it would make the world feel much more alive, therefore making you appreciate spending time in it regardless of which re-run you are making.
Like for example, if you have played World of Warcraft back in the day, if you loved some of the zones, you would never get tired of questing in them, even if that’s the 100th time you are doing it
I’m half on board with this. I also do not care about leaderboards. I do care about numbers though. And I would say that it is not a wild and outlandish idea that most players of “diablo-likes” also care about them in one way or another. Every time someone complains about balance good chances are they are complaining about numbers.
No, of course numbers are not th end all be all. But they are a huge part of the game.
The campaign is the part of the game where the numbers are still low. It’s also several tutorials, a canvas for the story, a forgiving part to learn interactions and items, a pathway to relevant endgame pieces that are not automatically unlocked with the story (dungeons, arena) and the main part for people that like to hunt easter eggs or secrets (at least I think most easter eggs/secrets are hidden somewhere in the campaign). And it probably has a few more reasons to exist that elude me right now.
Looking at these it does make sense that certain players don’t like playing a campaign over and over again (or just a few times). Most of it has to do with learning how the game works. If you learned all it has to teach (or think you did) I can understand that some people want to skip it to make it to the part of the game where the numbers are starting to get higher.
I personally don’t care much about the campaign itself. It was fun the first few times around, getting to know the characters, locations, quests, etc. After that I stopped caring about the story.
I still enjoy leveling though. And I still like the world (well except the ice area 
)
I would really love several mechanics/systems that make the campaign more relevant at end game. I think it is a shame that LE treats it mainly as a tutorial.
Grim Dawn did this very well with monster infriquents. Rare Items that only drop from specific enemies (some regular mobs, some heroes, some bosses, some quest related) that are only found in certain parts of the world. They have several versions for different levels. So playing a certain build makes you got back to a certain area if you need the build enabling (or just very nice and strong) bonus the item gives to your build.
Then there is faction farming that unlocks certain very strong mobs that are called Nemesis. So you also need to revisit certain areas to unlock and farm these Nemesis.
Devotion shrines are like the Lilith Shrines from D4 just not shit because there not many of them. They also make you go back sometimes, or give you certain goals to reach in the campaign map to reach when leveling a new character.
But if you still don’t like playing the campaign all over again you can level in the arena mode (crucible).
And in the upcomming expansion they are adding a way to customize your campaign/whole world with extra modifieres and an additional difficulty modifier that modifies almost all parts of the game.
TLDR: GD made the campaign part of the end game. And it’s fun and I love it. LE throws the campaign away after reaching monos - which I think is a mistake. Though to be realistic before they can actually improve anything system wise they probably need to finish the campaign first.
So yeah, while I don’t want a skip (I want fun leveling) the campaign is still a huge construction site. But with all that being said I still like the leveling process.