Why make this post now? In the past, DK issues have been mentioned during pre-release PTS testing. This period typically only lasts several weeks. There is simply not enough time to fully address the problems in time, and because of that they often get ignored. By posting this months before Summerset Isles, hopefully this gives ample time to make the necessary changes for a complete rework of the class.
History
To really understand the issue, it's best to take a look at back at the history of Mag DKs and compare their power to the other setups at the time. A brief history would be:
[Beta/Craglorn] Mag DKs have high costs, but could drop many ults with cheaper standard and fast ulti gen so they got a lot of resource return.
[1.6] Standard cost increase, ulti gen massively reduced across the board, high costs still exist, class is borderline unusable.
[CP Update] Champion Points come out which reduce magicka cost, and acts as a band-aid for the ability cost problem
[Morrowind] Sustain reduced across the board for all classes. DKs, who have the highest costs and worst sustain, get impacted the most by this.
[CWC] Can be made usable is with Flame Lash. Even then, still one of (if not the worst) PvE setups in the game.
[Dragon Bones] Flame lash, the only thing making sustaining DPS possible, gets nerfed.
There is a consistent pattern here of Mag DKs being in a very bad spot and reliant on one skill/mechanic to function properly, only to have it removed later. Ultimate gen originally kept sustain great, then it was nerfed. Champion Points helped keep sustain okay, then cost reduction was removed. Flame Lash was a last resort mechanic to not immediately run out of magicka, and it was nerfed.
So why are we in such a terrible position? We're simply out of band-aid solutions.
Current
Let's look at the current role of the Dragonknight in the meta right now. They currently still make great tanks for endgame content. However, they are quite possibly the least effective setup at other roles.
Dragonknights as a healer has never been a thing. It is slightly better than it was at release because of the changes to Cauterize and Obsidian Shard. However, both of these skills lack any real consistency, which is extremely important for being a healer. Mending from Igneous Shield is probably the only thing that would make DK healers even semi-viable, but a while ago this ability was changed so that you lose Mending when the shield goes away, making it much less effective. Aside from those skills, Dragonknights get absolutely nothing in terms of other benefits. None of their other abilities or passives would make any sort of impact on a healer. However, I think most would agree that this is probably fine. Not all classes need to excel in all roles. If DKs lack of healing potential needs to be sacrificed to make them viable in the tank/DPS roles, than it is probably worth it.
The core of the problem is most relevant when you look at Dragonknights as DPS. I will avoid talking about Stam DK in this post, because stam setups are much more homogeneous. Mag DKs have had problems in the past, but it has never gotten this bad before. Mag DKs are in an terrible position right now in terms of their damage output. There are three types of viable DPS niches to fill: Ranged Magicka, Melee Stamina, and Melee Magicka. Mag DKs fall into the Melee Magicka role, which is the worst of them all. You lose the safety and convenience of range, while not getting any of the DPS benefits from stamina.. Melee magicka setups should be atleast on an even level of DPS compared to melee stamina, but unfortunately this is not the case.In fact, practically all ranged setups do more DPS than Mag DK anyway. As a Mag DK, you get all of the risk and none of the reward. There is absolutely no reason to bring one into any form of endgame PvE content at all right now. You are a major hindrance to a group by not being a more meta setup.
Solutions
There are many things that could be improved upon in the DK class. That is what I would like to see be discussed in this thread. Zenimax can certainly change the class in any way they see fit, but they might appreciate us throwing out some ideas.
One thing to look at would be improving upon the unused morphs in the DK skill tree. There are a myriad of morph options that see little to no use at all. I would assume with these, less than 5% of DKs choose these options, but I am sure Zenmiax has more data on morph selections. Some of these morphs are: Cauterize, Hardened Armor, Reflective Plate, Obsidian Shard, Fragmented Shield, Shattering Rocks, Cinder Storm. Some of these may serve an extremely niche purpose like with Cauterize for healer builders or Cinder Storm for off-meta PvP tanks, but could still be improved upon.
The next thing to look at would be giving DKs some sort of reliable sustain. There are quite a few of options here as to what could be done. It could be either through active abilities or through passives. Something like magicka steal on Molten Whip would be interesting,
The last thing that could be done is simplying doing adjustments to the current numbers on the skills. Mainly, increasing damage and lowering cost. For example, a simple way to increase PvE DPS would be to greatly increase the damage of Eruption. Magicka cost being decreased on several skills would be very welcome aswell, but I think the majority of the sustain issue is going to have to be through other means.
If you have ideas, please post them below. Ideally, Dragonknights will be in a better state than they currently are when Summerset Isles drops.