I loved Resto Druid healing (back in Wrath of the Lich King). It's a lot more active and fun (for me) when compared to other healing classes. You're constantly casting spells, instead of casting one spell and then just standing there doing nothing for 10 seconds.
Also, you get to move around. Being a mobile healer was awesome. You weren't stuck to one spot spamming spells with cast timers.
You could cast other HoTs besides Lifebloom. I'll talk more about this later.
Cataclysm has removed the Resto Druid's active and mobile healing style. Now, you cast a spell and then wait... and wait... and wait... (assuming your tank/group isn't dying). This is very boring and not fun for me at all. I didn't sign up to be a pseudo-Holy Pally. If I had wanted to heal like a Holy Pally, I would have rolled one.
So, here's my suggestion: please revert the Resto Druid's healing style back to the way it was. Let us use all our HoTs. Let us be effective mobile healers again.
Why do I love HoTs? Well, they make Resto Druid healing unique. Let's pretend I'm healing a tank (back in Wrath of the Lich King). I could start off my healing by stacking up Lifeblooms. Is the tank ok? Nope? Then, I'll add a Rejuvenate. How about now? Nope, the tank's hp is still dropping too fast. Then, I'll add a Regrowth. How about now? Nope. Then, I'll add a Swiftmend, or a Nature's Swiftness + Healing Touch, or spam Nourishes, or spam Regrowths, or toss in a Wild Growth, or all of the above.
Basically, I could scale my healing very dynamically based on how much damage the tank was taking. I could ramp up and ramp down quite smoothly. There were many choices available to me.
These choices have been removed in Cataclysm. I can still roll Lifeblooms, but if I try using Rejuvenate or Regrowth, I go Out of Mana fast. This makes my healing choices quite limited and it's not very challenging anymore. I don't have to worry about refreshing all my different HoTs anymore.
Possible Solution: please make all our HoTs mana efficient again. If you have to choose one HoT to keep mana inefficient, please make it Regrowth. Punish us if we're spamming Regrowths. Obviously, Blizzard would have to adjust our HPS to match that of other healing classes.
I just want to be able to cast all my HoTs again. And be mobile.