Instead of overeacting, how about we look at the numbers. Foe: ~10% more magic damage, 3 sec cast. If all bard damage was magical it would take the bard himself 30 seconds after Foe to start seeing the damage increase. Unless you outdps a bard as a healer (which I find unlikely since you have less dps buffs and a lower potency rotation AND you also have to heal AND watch your MP), it will take you longer than 30 seconds to make up for the 3 second loss on the bard. It's proportional to your own dps. If you are doing half the bard's dps it will take you a minute to gain as much from the 10% buff than the bard lost by casting it. During AoE, the bard may need to sing the TP song more than a marginal dps increase if things are taking more than 30 sec to die. Or MP song, considering 30 seconds of WHM AoE will make you go oom even with Assize. On single target there might be a use for Foe without caster dps, assuming you can dps almost non-stop as a healer and the fight lasts long enough. A good example is the morbol boss in Arboretum. A trial with only 2 healers doing magic damage could also be a situation where Foe is useful, if the healers are both doing enough damage within the duration of Foe and don't have to heal much, and no one dies. Although in DF that's probably rarer than a singing bard.
So no, I'm not enabling bad habits. A bad habit would be not doing dps because you're too busy casting an unnecessary buff to a healer who won't make enough use of it. That's no better than a BLM spamming Physick when a healer is present. Realistically a single healer's contribution often isn't enough to warrant using Foe and I'm saying this as someone who also likes to dps the crap out of things. Using songs isn't as black and white as a few posters ITT would like to think. Depending on the situation it can be better to not sing, like it or not.