I think it's a good idea to make Diurnal default stance.
And while we're at it I think it's also time to get rid of that awkward 5sec cooldown on stances. I never got the point of it because you can only switch out of combat anyway. Why add a cooldown on top of that? It only makes stance dancing between pulls more risky as it increases the chance to get locked into the "wrong" stance and plenty of AST stay away from it because of this.
And if they want to avoid people accidentally turning off their stance altogether because they spam-clicked it: 1sec cooldown is enough.
I sort of got it with old cleric stance because it was meant to be risky and force you to plan ahead. But with something that can only be changed out of combat anyway? Meh.
And regarding the off topic discussion:
If people die to raidwides on e7 and e8 that has nothing to do with the AST playing in Diurnal.
Raid mitigation is team effort, not a "healer only" thing. You are not meant to survive many aoes on e7 and e8 without at least one type of mitigation up. e5 and e6 are pretty forgiving and you don't get one-shot if you're somewhere near full HP at ilvl 480 but that ends with e7 where you get completely wrecked even in near 500 without mitigation.
Melee DPS: Feint, Second Wind, Bloodbath
Physical Ranged: Addle, Second Wind, Shield Samba/ Tactician/ Troubadour
Caster: Addle, Manaward (BLM)
DRK: Reprisal, Dark Missionary, TBN
GNB: Reprisal, Heart of Light, Heart of Stone
PLD: Reprisal, Pasage of Arms, Divine Veil, Intervention
WAR: Reprisal, Shake it Off, Nascant Flash
That's a lot of mitigation and emergency heals and it doesn't even cost them anything except for one lousy weaving slot compared to AST blowing MP + a hardcast on a raid shield. If they had to rely on Noct Asp. Helios/ Succor pre-shielding to survive mechanics they were doing something seriously wrong.
You can Reprisal pretty much everything and between Temperance, Neutral, CU and two tank raid mitigations you have enough even without a physical ranged to spread it evenly on top of Addle/ Feint.
But it's astounding how many dps say something like "just a sec need to put it on my hotbar" when you ask them to use Addle/ Feint or how many tanks reply with "it's just 10%, you can just heal it" when asked to use raid mitigation.