So I haven't played bard, and don't know the resist rates of Lull, but FD crit fails more often than people think. When it does, your option is either take the full pack to your group and hope they can deal with it, or jump on that grenade and get a rez. Yes you have Defensives you can pop but you can't wait for 5 mins every time you crit fail and sometimes you crit fail 5-6 pulls in a row. As others have said, you can group evac, shaman invis, clerics can root and mem blur for you. Its a group focused game, having a group that works together solves a lot of these problems.
Monks and bards fundamentally pull in different ways, and have ways different ways to deal with bad pulls. As Fell mentioned there's few areas where you're pulling a pack of 8 linked mobs, and most pulls i've seen have at least a 10-15s free area for you to clean up on a resist/crit fail (usually the first room you clear is less dense since both monks and bards need space). A bard can hold 6 mobs in place with mez, I've seen them do it. Yes it takes time to cast but thats where roots, snares and taunts from your team comes in, it helps give you time to control the situation. If you give bards a way to reliably drop off the aggro table like FD, why would anyone bring a monk or enchanter? Bards would be able to cover pulling, mana regen, haste and cc.
All this being said, they should probably reduce the fail rate on Lull, whether its from scaling CHA or some other fix, so that it's roughly in line with how often FD crit fails and ruins a pull. That way its roughly the same for both pullers although monks have the advantage of trying riskier splits (they're supposed to be the premier puller).
