Look at these numbers, updated very often. 2+/13H players only.
Balance - 0%
Feral - 45%
Guardian - 0%
Resto - 0%
The ONLY reason why Feral is viable with DoC is because Predatory Swiftness makes your next Nature spell instant and not drop Cat Form. While it does require a lot more focus and precision than other builds, it's still very hard to play and performs very well when executed properly. Even then, for DoC's intended purpose of off-healing the raid (somewhat) is just adding difficulty to the build. Honestly now, no one trying to maximize their damage will Healing Touch the raid. It's either macroed to themselves or a tank.
The issue is how strict DoC spellcasting truly is. If you're casting Healing Touch, then Cosmic Barrage is being cast in your direction -- well you got interrupted! There goes that 2sec of hardcasting, try again! It would take you nearly 5sec to get your rotation back in order. As a Balance druid, if you lose 5sec like this, it's probably during Nature's Grace as well (losing 33% of Nature's Grace is awful)...and with nothing to show for it. When the little disruptions start to add up, you begin to realize just how flawed this "off-heal the raid and deal damage" becomes.
Heart of the Wild (HOTW) is better passive damage. Nature's Vigil (NV) is stronger burst with passive healing to the raid through damage output. These talents are simple to use. They have a clear intended usage (use NV with your big cooldowns), use HOTW to pop a ridiculously strong Tranq, or DPS for a little while when not tanking/healing. Above all, there really isn't much to pay attention to. You can focus on your core abilities. You cannot do this with DoC. As a Balance druid, I'm used to the idea I need to be in a particular Eclipse at a certain time, sometimes I need to adjust my spellcasting to speed up or slow down. I'm trying to predict where I will be in Eclipse, and where I need to be 30sec in advance. Certainly not something that can be called "easy" or "faceroll." With the added complexity of DoC, DoC becomes too difficult to use for it's reward. I know I can pull the same DPS with HOTW or NV, so why would I purposefully subject myself to such a brutal spellcasting system, such as DoC?
Below are a few suggestions to DoC. Having four (4) specs completely different from one another does not make DoC easy to balance. Making DoC tuned to each spec will simply bring better end results.
Whenever you use Mangle, you gain Ursoc's Resolve, causing Mangle to deal an additional 2% damage. Stacks up to 5 times. Whenever you reach maximum stacks you gain Blessing of Ursoc; the stacks of Ursoc's Resolve are consumed. Blessing of Ursoc allows your Healing Touch to be cast in any form and reduces the cast time of Healing Touch by 100%. Healing Touch cast this way will always be a critical hit. Stacks up to 3 times. Lasts 60 sec.
Your Wild Growth, Rejuvenation, Lifebloom, and Tranquility will grant the druid Blessing of Cenarius each time they are applied to friendly targets. Stacks up to 20 times. Every time 20 stacks are reached, Blessing of Cenarius will be consumed. Up to 3 nearby friendly targets are healed for [2041 + 45% of Spell Power] individually. Blessing of Cenarius also helps to cleanse the area around you, dealing [6045 + 54% SP] to enemies.
(WG only applies one stack per cast, Tranq applies 1 stack per HOT application)
Your Healing Touch grants your next 2 melee abilities 25% additional damage. In addition, Healing Touch is duplicated to 2 nearby friendly targets for 50% of the original amount.
Reaching an Eclipse state causes you to radiant with energy, healing up to 3 nearby friendly targets for [6071 + 50.3% of Spell Power]. When dealing damage to targets below 35% health, your Starfire, Starsurge, and Wrath will extend the duration of Moonfire and Sunfire by an additional 4 sec.