One of the main problems is that due to how the system is designed, you're not going to get a 20% reduction on Assize unless you play in a very specific inefficient manner. As others have stated, it will take about 38 seconds on average of doing nothing but spamming cure to hit 3 lillies. During this time, you cannot use Asylum, Tetra, or Benison. Then you finally hit 3, use them to knock a whopping 12 seconds off your recast, start cure bombing to build lillies up again, and on average you will have a mere 10 seconds, about 3-4 GCDs, to actually dps. This is most assuredly NOT using the new mechanics to give you massive amounts of MP and free time to DPS.

Alternatively, you can play like we currently do, utilizing regens most of the time to keep the tank up and only really needing to toss out a cure or cure II when a tankbuster hits or they've got everything from here to doomsday on their ass. In which case, you'll probably only see one lily, if that. So, best case scenario, you shave a whole 2 seconds off Assize's cooldown! I'm sorry, 2.4, you need the decimals when working with numbers this small. And that's assuming you literally remove Asylum and Tetra from your hotbar and never even bother putting Benison on it.

So, yeah. No matter how you look at it, the system as currently designed encourages you not to use a significant portion of your toolkit, and in return you get barely any increase at all. Even NOTHING would have been preferable, then we wouldn't have folks screaming on the forums about how spamming cure and cure II is the "proper" way to play, and that actually using the more efficient regens is playing the game wrong.