While several of the changes to NBs seem desirable (e.g. ditching the worthless haste), the decision to remove the heal from Sap Essence seems like a poor design decision. NBs tend to get pigeon holed into being DPS, but with the current Sap Essence it is viable to build a draining/heals build and a tank build that are fun and viable (even if they are not as powerful as the DK-tank and Templar-heals builds).
I suspect the train has already left the station, but I would ask that the folks @ ZOS take a look as this and consider whether they they want to further narrow the NB class or if it is possible to change one of the other abilities to restore the AOE drain to heal mechanic.
I would note that both Agony and Cripple are pretty nearly worthless and could be replaced with an AOE drain/heal power to replace the old Sap Essence.
Just my 2 cents.