First time around is for the story as the game was "meant" to be played. Second time around in NG+ is for the pure enjoyment of watching Dr. Strange cram buffs and heroism down Tony's throat as Tony makes every card draw about himself so he can keep jumping in the air and annihilating multiple city blocks with his rockets twice a turn. Or seeing how much block you can smear onto Cap while taunting every monster.
It's just for the good brain juices making numbers go up and that sweet sweet punching Hydra sensation.