Except for Arm's Length, I 100% agree.
Arm's Length still gives you a choice what and when you want to immune yourself against a knockback. If it still would be on 60s CD as it was the case in SB, I would've agreed. We would be able to counter every knockback if it remained that short of a CD. But since it's 120s now, I don't mind it staying the way it is... or at least bake it into other actions (e.g. Warriors IR).
Lucid Dreaming really doesn't make any sense on any caster right now. SMN already has so many phases and actions that reduce your MP cost to practically 0 (Egi Assault, Pheonix Trance, Tri-Disaster instead of dot-casting), RDM didn't have any mana issues since the start of ShB either (after they reduced the MP cost with an early patch), and BLM... no problems for obivious reasons...
It's really just there as a button bloat for healers because their actions are gosh dang expensive. Healers are the only role with high costs on their spells, starting at 400 MP on single target, and 600 aoe, whereas casters average spell cost is 200 (Ruin, Jolt, Verfire/-stone), and 400 in aoe-spells (again BLM is a special case).
The CD reduction from 120s to 60s (from 4.x to 5.x) also makes this action just more annoying/spammable and useless, because it also lost its more important enmity reduction effect... which again is useless now since the enmity adjustments. 60s would've made sense in SB, but it really doesn't in ShB. Someone behind the design team just didn't think this through... or was just adjusting this action with DPS (death/rez) in mind.
I would really like to see spell costs for healers reduced by 100/200 MP, and see their unique mana refresh actions reviewed (Assize, Draw, Aetherflow... EnergyDrain will probably be removed anyway).
On Shirk: I have nothing to add. I have barely seen it being used efficiently since the start of ShB, and more like out of habit. You've made an excellent point!
This!
To this day I don't understand SE's way of thinking with the homogenization process. MCH never had an "aoe mitigation" action. Dismantle (and Rend Mind) were always single target. Scrap Tactitian, and reintroduce Dismantle as a similar to Reprisal on target action (-x% dmg dealt on target + nearby enemies in y radius).
Troubadour can stay the way it is, and Shield Samba... well, can make a shield instead of %-mitigation, or vice versa.
But I would like to see all of the ranged dps mitigation actions getting reduced CDs (to 60s/90s). 120s is way too long, especially for support jobs.