hoegenaamd
Here is my current gear:

Here is DPS:

Context for saying other classes doing 5b-6b:
Saw a SA doing roughly 14b DPS with, I would assume, only class buffs and similar gear to my own with the only difference being +12 Circulation of Autumn manteau and Corresponding Left Accessory.
I highly doubt that if I were to get HoL gear and Nebula robe of spell at +12 Grade A that my DPS would suddenly sky rocket from nearly 4b to an additional 10b like the SA that I witnessed.
I do not know which patch or what their card setup is in your screenshot, but I can guarantee you if that guy in your screenshot were to move his gear over to literally any other magic class, they would absolutely crush the game without needing the durability skills that seems to be your main discussion point simply because they would remove the mechanics from the game via ungodly amounts of DPS.
Once again, I understand that IG is primarily a tank class sub DPS, I completely understand that, but that role becomes diminished borderline not required in the face of overwhelming damage. If the solution is, "go play those classes then", then I would retort with, just delete IG from the game. If ToT is brought up as needing a devo tank as the sole example to not removing .4 seconds of internal CD, then I would retort with, make every party designed instance require devo by applying ToT mechanics to those fights.
Other magic classes can solo and remove mechanics from "party" encounters because they do ridiculous amounts of DPS that is quite simply unobtainable by IG, hence why I suggested reducing the CD from 2.4 seconds to 2 seconds, so that way the durability that IG has can become more useful as the fight will not drag out longer than it does now.
I challenge you to find any kRO video of IG soloing Constellation tower/Encroached tan Hardmode, but I am 99% positive that you never will.
Don't worry, this suggestion was not aimed at dethroning/removing fun from the game for the top 3 magic classes, they'll still stay top tier meta. IG, with this, I hope anyways, will simply be more competitive rather than just get completely relegated to, "go play devo or play something else"
Funnily enough, you wouldn't even ask an IG to tank, because you would just ask an EM to tank (amazing how that works right?)
On a side note however, I did see iRO videos of genesis ray auto cast cross rain is a thing, please do not add that to the game, that is simply ridiculously overpowered, glad we're following kRO.