Quest progress should be shared between all difficulties. The difficulties should just be a checkbox, like Veteran is now. There should be 3: Normal, Veteran and Ultimate.
Writs, Mandates and Merits should be removed. Rep gain should get a 100% buff.
The reason for these suggestions: doing the campaign multiple times is just not that compelling. And starting a new character in Ultimate is kind of annoying, because you have to fiddle with the Merits before you can start playing.
So you run through the campaign and finish the entire thing by around level 70… and then what? Grind totems until 100? For 30 levels?
I think you can probably just eat a bunch of merits/mandates, get some lore notes, go to Ultimate and hit level 30 and then do your single play through. That way we don’t have to revamp the entire campaign just so you can skip it a little bit faster.
Perhaps the checkbox difficulty is a bad idea. I’d be happy if I could make new character in Ultimate right from the menu, without fiddling with merits. I also think Ultimate should come with a 100% bonus to rep gain. That way new characters could hit revered in 1 Ultimate playthrough.
In this case, Veteran should not be a checkbox on Normal, but should instead just be the second difficulty, replacing Elite. And people should be able to make new characters in it.
If quest progress is shared what would be the point of doing any quests with new characters? They wouldn’t get anything from doing the quests apart from maybe some items that some give. How are they supposed to gain levels if they’re not getting any XP from quests which give you the most XP in the game?
You’re suggesting a major rework of the game by dropping Elite.
And what about the upcoming Ascendant mode that Ultimate will get with the new expansion? Should that be dropped or become a 4th difficulty or even replace Ultimate?
So you’re just too lazy to activate the merit and mandates? Takes like 10s while a whole playthrough is multiple hours. 
Yes, exactly. Creating a character in Ultimate should be 1 click. We can already do it in the game, it’s just really cumbersome for no real reason.