When people talk about druid gearing, they usually talk about throughput versus efficiency, and they talk about regen rates. Throughput is how much healing per second can be done if you don't worry about mana. Efficiency is how much healing you do per mana. Regen is how fast your mana comes back. All three of these are good, and it ends up being a three-way tradeoff.
In principle, the latter two can be combined, so as to make it a two-way tradeoff. The two goals would be maximum throughput versus sustainable throughput. Sustainable throughput is the amount of healing that can be put out without going out of mana.
Once we get there, I suspect most people wouldn't pay much attention to maximum throughput. You can always use cooldowns and apply pre-hots to get through the hard parts of fights, so maximum throughput should rarely be a problem. The real reason druids want better throughput, I think, is that it indirectly helps sustainable throughput. When lifebloom heals for more, you can spend less time casting healing tuch and more time casting nourish.
The level of sustainable throughput depends on how long the fight is. That's because you start the fight with a full bar of mana. With a very short fight, maximum throughput is the same as sustainable throughput, because even at maximum burn rate you won't run out of mana. As fights get longer, sustainable throughput decreases toward an asymptote. For absurdly long fights, the initial mana bar becomes irrelevant.
I haven't tried to theorycraft the computation of sustainable throughput. I would love to see any work that others have done on it. It is likely helpful to divide it into two components: one for the infinite-length fight that ignores the initial mana bar, and one that figures out the advantages of burning through the initial mana bar over the course of the fight. The full sustainable throughput is the sum of the other two.
Maximum sustainable throughput might not only affect gearing, but spell selection. In principle, it could even be helpful to pause for a few seconds and, let mana regen, and then cast a more effective spell after a few seconds. I don't know whether that's really true or not, but in principle it could help. Sustainable throughput gives a way to analyze decisions about spell selection.
Sustainable throughput is more valuable when damage is less spiky. With spiky damage, you just have to drop big heals on the tank so that they don't get gibbed. With slower damage, you can afford to wait a few seconds and do things more efficiently.
All in all, I'd like to see more emphasis on sustainable throughput. It looks clarifying for gearing and spell selection, especially with Cataclysms smoother damage patterns.