What about that was fun? I'm actually curious about the specifics.
How I spammed pom/bubble as fast as I possibly could, then used other abilities when unique situations came up. Or pom/renew/coh style was fun. I liked the PoH spam play style in ulduar a lot.
It was just more exciting. PoH healed 40% of people's health bars back then in a single cast. You had to pre-cast that crap for bursts from the boss. It was just "faster" and "more exciting" to me.
So, you spammed PoH. Can you somehow not do that now? Can you somehow not do that within a triage style fight?
The point of the triage is that you are still spamming this to heal people back up, but if someone takes additional damage from another mechanic of a fight, they aren't dead. You can choose to use other abilities when "unique" situations come and NOT fall so far behind in healing that you can't catch up. This system still promotes the proactive healing that you are also talking about but allows for reactive healing as well without just watching people die and nothing you can do about it.
Tank healing was terrible at the end of wrath because of the amount of micromanagement you had to deal with on every single boss ability.
Raid healing wasn't as broken but at the same time, raid healing was something that dictated a lot of the raids. It essentially caused every fight to either have a massive aoe damage ability or to have pulsing aoe the entire time. Because of the throughput of healers and the amount of mana available, it had to be designed into every aspect of the encounter. If you put this into an environment with spell costs on aoe spells are more significant, then they can free up encounter design to move away from the spam heal the raid the entire time. This allows encounters to be different.
Not to mention that I healed on a paladin and lord knows trying to deal with aoe healing during half the fights throughout that expansion was just about as fun as pulling teeth.
Lastly, I will mention that Ulduar really was the place where healing started to turn over in the "wrath" defined healing. You weren't really to the point that you never ran out of mana, and their was just enough balance between damage and healing that it wasn't as twitchy. After ulduar is when it really went downhill and that's most of what I'm talking about when I am mentioning this "wrath" healing model.