PoE’s is too long. Like, way too long.
GD’s campaign is the game, which is something few ARPGs get right, but it still also provides other activities, which is nice.
D3 and Wolcen only require one character to complete it, which I don’t mind.
Torchlight 1 & 2 and Dungeon Siege 1 & 2 are all about the campaign itself, except mods gave TL2 lots of alternate and endgame options.
As for how long it should be in LE, I wouldn’t mind the length if it weren’t for the confluence of it being extremely linear and the endgame making it largely pointless. This is why I advocate to either make it optional or rework it so that it stays relevant even into echos. The current design path points toward something more like D3 or PoE than it does Torchlight or Grim Dawn.
Basically, it feels too long if it takes more than a few hours (not speedrunning) and also feels pointless.