TLDR;: I wished the egg and back bug mutations were a thing to practice on any shard level, as two optional ‘hardmodes’.
It would allow veterans to practice and play together with newer players not ready for higher shards.
Reasons:
I don’t know about back bug, yet, but I expect it an equally odd mechanics like the egg one.
Now reading up on forums I was really curious to practice and find a rotation, class setup or anything which allows to proceed past the dungeon entrance 
, however, the week is over and between raids, gear-up runs and so on, we had no chance to go for another try.
Since we got too few people to have 2 groups we take turns and even if we level 10s in time, the group going higher will frequently change. Now each time requires a potion set and as it looks we are downgrading shards for a long while with no benefits, just to practice with everone.
Unlike raids you can’t just step in and start, the group is often already exhausted until we get anything up to 11. Every other mutation is easy to grasp and does not take that long time to adapt to, but I feel back bug and golden egg will, least for some groups.
So here comes the Suggestion:
I wished there was a “hardmode” switch where EVERY dungeon can have either of these 2 mutations added (one applying randomly is fine, selecting them would be even better). There could be special rewards for this, or for the first time doing one daily, like potions, additional glimmering shards or whatever.
But mainly this would allow groups to practice, test things with less geared alt-classes and give guilds like us another chance for an activity for new and old players/veterans alike.
I fear that groups who got the mechanics down, finally, are even reluctant loosing their high shards if they take in others to practice from scratch.
However, the many newer players in guild which are not able to perform in high shards, yet, could join this activity right from the start, so that they are prepared once they get there…
With some rewards added, a hardmode like this where we could proceed slowly, trying harder and harder shards while passing around the egg (possibly Airship excluded), could be fun I think.
(In case it gets picked up I currently think the egg should tick exactly like it does on a level 11 so it does not become trivial; but in case this is too hard to take lower players in, perhaps it should scale to the player’s gear levels or so.)