Map Objective Change Suggestion

Killing all rares in a map as an objective for clearing the map leads to some issues so I figured I would throw out my suggestion for a replacement.

Still have killing the map boss as an objective where applicable, but instead of killing all rares, kill a percentage (70-80%-ish) of the total Power of the monsters in the map. If this were the objective, killing rares is more beneficial for map completion, but leaving a rare pack or two behind can be overcome by just clearing more of the map. I guess some players may still have to backtrack sometimes in some maps, but it should be significantly reduced. Also the backtracking wouldn't be "move towards the rare monster marker", it would be looking for where they haven't explored. I think this would be more enjoyable and engaging for players.

Also, for me and players like me who generally want to reveal all of the map, we won't be tempted to just follow the rare monster markers when they appear and we won't know that there are no rares left when the map is complete. Knowing there are no more rares disincentives exploring the whole map as the best loot piñatas are all gone.

Thoughts?

TLDR: Instead of killing all rares, kill a percentage (70-80%-ish) of the total Power of the monsters in the map.