Bard AoE is a lot more involved than most people would think.
The usual thought process is this:
Priority 1: Locate the most threatening 2-3 mobs as a tank is mass pulling, and double-DoT those.
Priority 2: Assuming both Mage's Ballad and Wanderer's Minuet are available: If amount of mobs > 3, use Mage's Ballad. If < 3, use Wanderer's Minuet. Either way, you end up doing Quick Nock and either Rain of Death/Pitch Perfect spam.
Priority 3: Use Troubadour and Minne during mass pulls. 15% damage reduction means the healer will be given more leeway to contribute damage of their own/can save some of their cooldowns for the next pull. Also remember to use Shadowbite if you have it - Shadowbite's damage is based on whether the primary target is afflicted with both DoTs, with the same potency damage being applied to all mobs around the primary target regardless of their DoT status.
Priority 4: Remember to refresh the DoTs on the mobs you singled out to double-DoT.
Priority 5: (Oh yeah, if the mobs have something you can interrupt, do that too. Extra fun.)
Long story short, you're trying to juggle a lot of things. Even someone like me occasionally fumbles with one or two things during a mass pull (aiming Apex incorrectly, letting one of the DoTs drop, forgetting Troubadour/Minne, and so on). It's no wonder why Bards appear to have this reputation as being a class that can either completely destroy dungeons or end up being a liability as a result. Our AoE potential is actually way up there with Black Mages and Summoners, but it requires some pre-planning. I typically end up using the same songs at the same point in each dungeon run, depending on the party's overall speed (namely if the tank mass pulls or not).
I recorded a random dungeon run I did about two hours ago, where I actually ran into another Bard that was actually able to match me in AoE. I can probably count with two hands the amount of random people I've met in dungeons since the start of the expansion that were able to match or surpass my Bard AoE performance from ANY class.
https://www.youtube.com/watch?v=hqWt3zplni4
(Oh, sorry about the frantic button mashing in the middle of all of that too. Shame about our single target damage, though. Even two very good Bards can't come up with the personal damage needed to skip the second lightning field phase from the last boss.)