General Community Resistant to Healer Damage?

[EaMett]

40%? Maybe in a properly coordinated run where people only take the absolute minimum necessary damage.

I think you're overestimating the value of a healer and underestimating optimized settings. As a reminder, dungeon speed runs have often been done without a healer at all.
I don't even do optimized runs but when I go in with players from my static all the healing I need to do in ex roulette is basically an excog on tank for trash and a whispering dawn on the bosses.
Likewise when I run expert roulette by myself in the duty finder I still don't use a single gcd in combat. It takes a really under-geared tank not using any CDs pulling wall to wall to get me to cast an actual heal. Everything else is ogcd. Of course everyone's mileage will vary, based on skill, comfort, gear, etc... But the idea that spending 40% of your time healing in dungeons is a normal average is just incorrect. You would have to be topping everyone up always to hit those numbers and at that point you should really focus on sharpening your skills. hence all the "healers should dps" threads.

To get an idea of how much time is spent healing in content in semi-optimized to optimized settings you're looking at about 20-10% healing in savage, 30-20% in ultimate. That's a lot of time doing nothing.

Normal duty finder raids(8-24)/trials when content is new and mentor roulette duty finder extreme trials are pretty much the only places where healing becomes a significant part of your gameplay. But those are very limited situations.

I've played MMO's where random damage spikes were a thing and let me tell you, it's not fun. Never knowing when someone is going to be hit super hard based on RNG is stressful as hell. Predictability is important for both healers and tanks.

Yeah, people have different takes on it. The gameplay becomes less about timing heals and more about spamming heals and managing your mana cleverly. I found that once you make that abstraction and forget about the actual healing to focus on the actual mana management it became pretty fun. But alas, I'm sure it's not for everyone, just as dpsing as healer is clearly not for everyone.