I know that a few people (including myself) have brought this up before. First off, the 3 person limit was reduced on Salvage and it had a huge impact on the game - at least on Odin, it helped to revitalize the Alexandrite market. At one point late last year people were paying up to 20k each (seriously!), and now they are selling for 9-11k. It's amazing, and has made it so much easier to gather the Alex required, so thanks for that.
Einherjar is an older part of the game, and as such there's barely any interest in it. Most people are bored and done with Odin II. Abjurations are outdated, and there's not really any gil to be made from boxes. Because of this, it can be really difficult to find 6 people to meet the entry/stay requirements. Unfortunately, Einherjar is still a very much required part of the game for anyone who wishes to make a Mythic.
To give a little perspective, if you're starting off at zero Therion Ichor (with the end goal of needing 100 for the eyepatch), you'll need to do 53 T3 Einherjar wings.
Speaking as someone who's completed one mythic and is 5-6 days away from completing a second, Einherjar has been one of the biggest wrench in the gears in the mythic process.
It can be incredibly time consuming and painful to try to find six people to make a group. I've seen groups floundering for people for hours before giving up. Of course, there is the option to enter with less than 6, but with the high risk of not completing the chamber and not getting full points (and even if you do win, you don't get a chest).
So please, please consider lowering the person requirement on Einherjar, if not entirely to at least to 3 people.
Thanks for reading!