The problem is that even if you get a 20% reduction on EVERY cd over a given length of time, it's still not GOOD. Even assuming you get three lilies for every single oGCD you use and hit Assizes on the entire raid and three mobs, and Asylums on both tanks and two melee, you still get only slightly more healing potency and LESS damage potency than an AST who uses their ground effect on the tank and a single enemy. That's terrible, and it's assuming good luck of the you-just-won-the-lottery-twice-in-a-row variety from your Cure spam.
The confession system I'm much more sympathetic to - it essentially acts as a chance of an echoed Cure down the line, and provides actual tangible benefits if the content warrants that kind of Curebombing - one sort of ballpark way of looking at it is to just add 80 potency to your Cure/Cure 2 if you are going to spam a single target for a while, and since the CD on PI is so low, you certainly aren't going to have to worry about using it at the wrong time very often. It's less useful if the raids are more similar to how they've been in 2.0-3.5, but I can at least see how it fits into some theoretical boss fight. Lilies, though? At a 20% chance to proc, they are terrible even if we use NOTHING but cure.