There are a couple of videos in the spoiler if you don't know what Barttle's Taxonomy is.

I generally consider myself pretty strongly in the explorer category. I just like trying out new builds and setups and running different classes of healers in different dungeons, as well as collecting (well hording) recipees and motifs. That's how I get enjoyment out of the game. If I'm looking to play a dungeon, I'd rather play it NM and be able to use a class's unique abilities to heal in the dungeon instead of chasing meta and using all shared abilities. Those unique classes look something like:

Templar - Big Heals & Resource Regen
Warden - Buff Team Mates & Heal
Sorcerer - Pet Healer
Night Blade - Damage and Hot heal
Dragon Knight - Mitigation/shield healing.

In this sense, the murkmire updates pretty much destroyed the nightblade way of healing, but had nothing to replace it with. The shield destruction hurt the sorcs in non-group content since protecting pets is going to be harder. This is definately going to make the game appeal less to explorers. These changes were basically made at the behest of achievers who felt NB dd's were too strong and (for some reason) that shields were making healers obsolete in high end content and so they were nerfed. That same group seems to get really angry if you claim that there is another way to enjoy the game, and that way should be considered when making changes just as much as their views. End game balance is pretty precarious in both v-trail and for pvp, but not that important for explorers. Having one dd that can hypothetically do 10% more damage in a dungeon doesn't matter in the least, but can mean not getting invited to a v-trial. That doesn't mean that taking a sledgehammer to a class's abilities that aren't that important in endgame won't matter to people that enjoy early/midgame content.

Anyway, just a little food for thought. If the explorers leave the game because only achievers were considered, there won't be anyone there to make your training gear, sell you raw mats, buy the motifs that drop etc etc and so I think multiple people need to be considered.