Will this dodge roll and all these unique boss mechanics actually be relevant, or is it "100 new bosses to battle instagib, each with unique mechanics that you'll never see"? PoE1 has a lot of unique boss mechanics in theory, but you don't get to see much when the meta outside of early leveling and a handful of pinnacle encounters is "if you have to learn mechanics your build is too weak, rework your build so you can just kill the boss before it does anything."
In the presentation they mentioned that the whole zone resets if you die to the boss, preventing you from grinding down its health. That implies to me that they want them to be a more significant part of the game.