The argument"MCH/Bard have utility so their damage should be lower"

[Bishop81]

Check Duty Finder. There is no "support" role. It's DPS. Give us support slot and I'll buy that argument.

MCH do not have the same support as Bard. The only thing we really have is MP/TP regen and a long cooldown, situational damage reduction ability.

Unofficially there is a support role, it's just not a dedicated role. Heck, pre-Heavensward BRD's limit break didn't even do damage.

BRD/MCH contributes to raid damage (among other things) indirectly.

Raids aren't about you, it's about the raid.