Long wait times for DPS in low level dungeons isn't exactly a new thing. It's even worse now as there are still a good number of people trying out rogue and ninja. I don't think that there needs to be an exp boost, because what is stopping you from fate farming or doing leves while you are waiting for the queue? If you aren't leveling a character and doing it for animus or something, grab a tank or healer friend. There are a lot less tanks and healers in FFXIV than there are DPS. It's only natural that the wait times are longer due to supply and demand.