BLM dps and utility...

[Sleigh]

All the DPS have a role.

MNKs have highest (or second highest) sustained single target DPS.
SMNs have really high sustained DPS, great AoE as well for medium length encounters. Plus a Resurrection you can use if things go south.
BLMs have high sustained DPS, have super burst damage, and when it comes to extended fights they have top AoE of the DPS. Plus nothing beats the burst of double Flare. They have CC but considering there's nothing you want to CC in this game (gear depending), that's a moot point.
DRGs buff BRD damage and are damn good at burst damage as well. TBH, not sure how their sustained DPS REALLY stacks up to the others but in my experience it's on the low end of the DPS classes. In theory any party with double Bard should be rocking a DRG, gear considering.
BRDs may or may not have low DPS compared to the other DPS, but their songs, mobility, and AoE are no joke and have a place in every fight. Most of Coil has roles BRD is best at or essential to have for the strategy to succeed.

As for BLM vs SMN, I like SMN better for most situations. The only situations I really appreciate BLM more is when you need to kill something ASAP, or when there's an AoE party (like speed runs, good as SMN AoE can be nothing beats killing a set of 7+ enemies from 50% life within 5 seconds)