I think that the change about disengage being a bonus action has been made to make the combat more interesting. It is obvious for a tabletop player that in order to disengage as a bonus action, you have to be a rogue, but it is not obvious to a casual player who might think "hey, why Astarion can jump/disengage as a bonus and my Heavy Armor Warrior cannot?" It's obvious for 5e players and DM's, but not for a random player who could feel like he wasted time by playing a class that cant jump and attack in the same round.
Looking at this, jump should be a bonus action, but it shouldn't ignore Attacks of Opportunity. They just need a separate Disengage ability that takes a full action to use to move out of melee for Attacks of Opportunity.
