Something I haven't seen discussed a whole lot is how to nerf the healer class as a role. We talk a lot about how to fix each individual healer, but let's just take a second to admit that healers are exceptionally powerful in the current content. Healing is a breeze even in some of the Savage raids and still leaves us room to DPS. Hell, SCH is basically a 5th DPS.
So let's switch gears and talk about nerfing from the angle of the content itself. Yes, bigger numbers hitting the tank would put a slightly larger strain on our Cure button but we can take things a step further.
In dungeons we can add a couple more trash mobs per pull, but what about easily identifiable mobs that have mini-tank busters (like those bees but less extreme and without the self-sacrifice part), or roaming monsters that spawn at a random location in the dungeon to keep the party on their toes? This would add a small variety to our roulettes without amping the difficulty too much but just enough to find those DPS windows harder to find and predict or create.
NM/HM trials could do with needing more work out of the off-healer, especially during add phases. Maybe more hazard spots or DoTs getting thrown out to other party members (the exploding healer mechanic from Ifrit EX comes to mind).
EX/Savage raids need the main healer to REQUIRE focusing on the MT, and this content could do with some more communication between tanks and healers. Tank busters that would OHKO a PLD even with a defensive CD (outside Hollowed Ground), but, say, a WAR could sponge. In this situation, let's say the tank buster would dish out 1k over the PLD health. The healers could top off the PLD and provide a shield the keep him alive and then focus heal him back up or have the WAR Provoke the attack and the PLD takes back aggros while the off healer heals up the WAR and main healer never stops focus healing the tank.
I want to know what you guys think. You can pick apart my examples, I admit I don't know a whole lot outside of WHM and a couple others I'm only now getting into so there are probably holes in thise examples somewhere, but the point is to think of ways to make the content itself nerf the healing role instead of strictly thinking of what traits/actions to remove/add/alter.