A bard is a DPS job that trades off some of its raw DPS in exchange for utility (songs) and stable damage output in nearly all situations. Look at any DPS job and you'll see a sliding scale between raw output and utility.

Certain jobs are very fussy about range, buffs, movement, flanking, etc.; bards don't have to deal with any of that.

Songs are super useful. I'm not certain what reality people here are playing in where TP and MP regen aren't needed, but it's not the same experience I've had or seen.