I don't honestly care why the healer is low on Mana. As a bard, Balad is one of the main reason's I'm useful to a group. If I see that the healer is low (Especially under 1.5K), I go ahead and assume they've used their CDs already and Balad + Voice. Once their Mana is back up over 3K or so, I turn it off and keep doing my thing.

If the party needed another pure DPS, they'd have brought along something other than a Bard. If you don't want to support your part, don't play a semi support role.