First of all let me say that Anet you created a great game (with your latest dungeon, the Fractals you took a big step in the right direction, keep it that way!).
Remove MF gear effects from dungeons!
I love the philosophy behind the game, that there is no kill steal, node steal etc. Everyone is rewarded for their actions. Moreover, if you do more you get better rewards (events) which is completely fair.
However in dungeons, there is no such system. You work together as a team and more or less get the same reward (from mobs/chests). Here comes the issue with MF gear in dungeons.
MF gear has 2 useful stats (power/precision, I know they added new ones but let’s go with this) to the party, and a 3rd stat which does nothing for the team. Let’s say I’m running with my warrior in full berserk set(power/precision/crit damage) glass cannon, and an other guy runs with MF gear glass cannon. Let’s assume we are equally skilled. My damage will be clearly higher due to the extra crit damage. I contributed more to the success of the team (killing a boss/ finishing an event faster). After each boss/event he has a better chance to get more/rarer loot, than I do, while in contribution I did a lot more.
Other issue could be that the player is not skilled enough without the 3rd extra combat stat and keeps dying, becoming a true hindrance to the team.
So the philosophy behind this is be less useful, and get more reward for it? I don’t like it. I’d suggest that you remove any beneficial effect MF gear has in dungeon.