I say flat out that I am new and I would like to map the dungeon (if needed). I've not had a problem at all with it. When I see people with the plant leaf, I ask if anyone needs maps or haven't run the dungeon before fully.

I've only once had a group that speed ran through a dungeon. But you know what? As DPS I just do my thing, and let the others worry about their jobs.

Speak up. If it's bothering you, then leave. There are other groups out there. It sucks, trust me, and a shame there is no Duty Finder option for Speed Run Only.