We really need to talk about Living Dead

[Rilifane]

Living Dead serves its purpose when you're in a clutch and would have definitely died otherwise. In those cases it's like a second chance for your healer to get everything back under control.
This counts for both dungeons and raids. If something went seriously wrong you may be able to salvage it.
The other tank invuls are admittedly much easier to handle without Benediction but it can still give you valuable time.

However when it comes to raids and using it for tankbusters, Living Dead usually adds pressure on healers instead of taking it away.
Depending on gear you need around 3200-3500 potency which is a lot. While every healer can solo heal it, they all need to blow several oGCD and GCD heals to make it in time.
A SCH/ AST comp will, in most cases, need to use more resources than they would've used if the tank simply took regular damage with some mitigation up. Even if you're really lucky with high rolls, Recit Excog and ED crit is not enough, you will need a 2nd ED and/ or Lustrate in addition to DRK selfheal and fairy autos.
The longer duration of LD is only a boon if a mechanic hits several times so they can take more hits compared to other tanks.
But in most situations it only puts unneccessary pressure on healers and completely messes their distribution of tank upkeep resources up.

Compare that to GNB: it brings you to one HP and you have 7sec to heal the GNB above auto attack threshhold while the tank takes no damage at all.
WAR: you can ignore the tank until Holmgang almost runs out and bring above auto attack threshold. Even easier if it was something like 14 or e7 TB where the OT won't take any damage after the one big hit and you have all the time in the world to heal him back up.
PLD: god button. Period. Healers love it.

Haven't progged through e8 until enrage yet but for e5-e7 I can safely say that DRK invul only ever made my life harder than easier when paired with SCH/ Bene wasn't up.
Yet many DRK insisted on using it to "cheese" tankbusters when in reality, it only made it worse. It needs careful planning and holding back resources which makes it inefficient over just eating the damage with mitigation and healing it efficiently and at your own pace.

I'm against streamlining invuls but some form of tweaking that gives it more uses for current encounter design regardless of healer comp would be nice.

As for the others being "less stressful", this should be a non-issue. The first thing the healer should look at when getting into a duty is the job icon for the tank, which will dictate, among other things, the appropriate plan for dealing with the tank's superbutton. If you're in a party with a DRK you should already know that it's possible you will be required to heal them to full in the span of a few seconds, just like if you're in a party with a GNB you should know that you don't need to be alarmed if their HP drops from 120,000 down to 1 in an instant. The answer to the potential stress of these two abilities is awareness and readiness.
.

The purpose of superbuttons is:
1) oh shit I'm gonna die, time to invul!
2) making situations easier

The latter is basically never the case for DRK invul in dungeons. So preparing for the tank to use an invul that makes it worse on a whim is questionable. I mean, yes. We should be prepared to deal with all types of bad decisions but with how invuls work, you will constantly need to hold back some resources just in case the DRK decides it's a fantastic idea to grief his healer.
All other invuls can be used and dealt with on a whim.
The DRK is the only oddball where using the invul outside of "oh shit" situations feels punishing escpecially in dungeons.

Solo healing a DRK invul in a big pull takes several GCDs/ ogCDs and renders the healing useless because they still take damage. You basically just forced a healer to do what they have to do anyway but in a much more inefficient way because of the added timer while not gaining anything.