I enjoyed the world drop system much more. I I fall into the min-max endgame crowd, and with the release of Mayhem 2.0 nearly all viable weapons became exclusive to dedicated drop farming. I actually hate save quit farming, it was my primary grudge against BL2.
I would LOVE to see M6+ weapons added to the world drop loot pool. You would still have to play in higher Mayhem levels. The chances of getting them to drop would still be extremely low with the world drop loot pool. But to be able to see a Kaoson or Plaguebearer etc. drop in Slaughter Shaft would be much more enjoyable.