The designers were clear in their intent. They wanted two primary changes from Wrath 1) make mana matter and 2) make healers diversify spell choice. The objective of both changes was ostensibly to make healing more fun.
For me, healing is definitely not more fun. I spend the majority of the casting seconds in any encounter casting the least dynamic spell in the game Heal - it’s a long cast time and hits with the same punch as my granny. Instead of spamming PwS, I am now spamming Heal. Is there not a way to have a model where we don’t spam any button? I would love to use all my tools roughly the same amount of time - save for those with CDs for obvious balance reasons.
I don’t think that is what really bothers me about the new healing model though. I think what really bothers me is that a healer is actually encouraged to heal as little as possible. Because mana is the most important concern for any healer; the best healer is the one that conserves that resource as much as possible. I can’t imagine why one would want to play a DPS class if your primary goal was to use a finite damage pool as efficiently as possible. What makes every other role fun is knowing how to use your tools, on what target, at what time, as quickly as possible. That is where I wish healing was. IMO, it is not.