The issue with masteries now is that unlocking them primarily requires grinding easy content over and over. It’s not compelling.
By removing the experience requirement and slightly increasing the number of mastery points required, the game becomes about overcoming challenging content, but not grinding it.
In the jungle, players still need to run events for loot and to unlock the meta-event bosses (which hold achievements for mastery points). There’s already incentive to run them. This change would benefit the game.