I just finished the campaign and I totally agree with you that the dungeon bosses, and the story bosses in general, are completely boring. It’s probably not the biggest problem in the game (hello itemization and affix clutter) but it’s a problem nonetheless. Bosses are just giant health sponges. All bark and no bite. I beat Lilith and every other story boss on my first try with the maximum number of health globes in my belt when the fight was over. And this was on WT2 difficulty.
Imo the campaign bosses would have been epic if they had half the health but were harder hitting, and required strategy or dodge mechanics to defeat. HC players would hate it but they’d just have to learn on SC first. For dungeons, imagine if the boss you faced at the end had the affixes of the item power you were trying to earn. That would be quite immersive and logical, wouldn’t it? I’m speaking to the campaign here. I don’t know anything about the end game yet.