General Community Resistant to Healer Damage?

[Lilseph]

But what about the rest of the game?
But -a little- more danger should be in the cards, no? A little more incoming damage.

Generally those kinds of mechanics and damage thresholds are sectioned off for a reason. Particularly with incoming damage because the Devs have to always balance that so that it's possible to complete with the set minimim ilvl (see: that bug with Mog King and Memento Moogle). Tbh, I don't think people would enjoy running a dungeon that forces you to min ilvl as a daily roulette.

If content was a bit meaner, we would heal more.

Not necessarily. Healing has always had that inherent flaw. If incoming damage necessitates spamming the Tier 1 Cure to keep the tank alive, then there isn't enough incoming damage to warrant spending GCDs using it. Regen and oGCDs handles that way more efficiently and with fewer button presses. If incoming damage necessitates both healers spamming AoE heals to keep the party alive, then you have TEA's Judgement Formation with both healers bottoming their MP within 45 seconds. Healing in this game just isn't built for sustained constant healing.

Add a few more DPS toys to move away from the "mash [1] for 28 seconds, then refresh your DoT" and it would be perfect.

I'm all for this just to break the monotony lol.