I'm a new player who just beat ARR. I've noticed whenever I enter a dungeon, a message pops up that says a new player has joined and there is a bonus for completing the dungeon quickly but the same message doesn't appear if all players have completed the dungeon before. This is backwards.

My first class is a white mage. Even after beating ARR, I know very few of the mechanics in dungeons because no one takes the time to explain them to me. They're so focused on getting through the dungeon as quickly as possible that I'm just frantically chasing and healing the tank while knowing nothing about the boss fights or keys I need to pick up or whatever.

It's especially important for new players to understand the mechanics and to have a casual experience in dungeons. I did Crystal Tower recently and I know ZERO mechanics. I announced it was my first time and no one said anything about what I'm supposed to do or avoid and in those fights you HAVE to know mechanics otherwise you'll die instantly - which I did many times. Since I'm a healer, it's kinda bad I was dead half the fight.

This severe lack of knowledge became painfully apparent to me when I tried doing a Command Mission. I'm solely responsible for doing the entire dungeon myself and yet I had difficulties with the very first one because I didn't understand mechanics.

This should be easily fixed by simply flipping the reward system. Don't give a bonus for a new player going through the dungeon as quickly as possible. Give a bonus for the fact a new player is in the dungeon without a time limit. Then if the entire party has gone through the dungeon before, give a time completion bonus.