Far more than efficiency is needed for some approach to become the norm: it needs to consist on easy enough tactics to be reproduced up to a high degree by evarage-ish skilled PUGs.
When this doesn’t happen, several metas usually appear, with dedicated guilds taking the optimal approach while PUGs resort on some suboptimal but easy to perform tactics.
For this kind of encounter it’s actually quite difficult to develop a fixed strategy. The fight is quite lengthy and the enemies we’re going to fight against are randomly selected, so there’s no way to tell how many of each defensive tool (condi clears, reflects, …) would be desirable and when should they be used.
On top of that, the fight involves several damage sources, making far more difficult to be aware of every threat we should avoid.
Control, something mordrem enemies are specially weak against, is probably the key to handle this fight confortably.
Control doesn’t depend on raw stats and most offensive specs can slot some amount of it without giving up too much damage. A group of experinced players on some kind of voice comm could beat this encounter by efficiently rotating their distributed control while on quite offensive specs.
When players are unable to play coordinatedly, however, controling tools can be wasted and damage spikes against piority targets can be lackluster. In this situation, more enemies can land their attacks, player active defenses might get exhausted and eventually damage happens.
I’ve no idea on how the playerbase would adapt to this fight.
Losing a player at the very beginning of the fight can easily snowball against the group so maybe being extremely squishy is not a good idea. On the other hand, being able to dispatch some enemies as fast as possible can be highly desirable (and finsihing the event faster always award a better reward/time ratio), so a high damage output is still a good thing. Maybe mixing some sturdy body that can pick up allies under heavy pressure isn’t a bad idea at all (as long as he can do something more, obviously, just being sturdy is not a great deal for a group).
A character heavily specced into control might also not be a bad idea, even if he gives up a good amount of damage for that. It would be clearly unefficient when compared to a good usage of distributed control, but it would lessen the need of coordination and that can be enough to make it worth.
Same goes for healing. If you expect things to get out of hand at some point, a bit of extra healing, even if it’s at the costs of damage, might not be a necessarily bad choice.
This could become even more true with the risk vs reward idea being properly handled, which in this case should AT LEAST force the group to restart the whole event on a wipe.
In short words, the fight is much more prone to mistakes and snowballing than most the current ones, and definitely much more about real time combat than about tactic execution.
We could move away from the current situation, where we know that some well executed tactic flawlessly works and including too much room for mistakes not only is uneeded but often goes against the tactic itself, to a completely different one where mistakes are much more likely to happen but far less punishing individually, so a larger amount of specs can be truly helpful on their own way.
Note: there would still be A LOT of plain BAD specs, doesn’t matter how much their users loves them, and a lot of complaints over the forums. There’s just no fix for the lack of common sense.