So BLM as AOE covered, MNK has single target... What does SMN bring?

[ViviAnimus]

There is no viable reason to bring a Summoner. Damage wise Summoner starts out great, but the DPS just drops and drops and continues to drop. There is no real way to get the DPS up, at all. Once is drops, have fun, because it will stay like it is or drop more. This is my experience and I am definitely not a bad player / summoner / black mage.
If you fully utilize your rotation, you will most likely run out of MP and therefore the BRD will have to play ballad. So you are causing a decrease of overall team DPS for being good at DPS, on top of that your damage isn't that great anyway in comparison to other classes. You have the advantage over Bard, but not by that much, to be fair. A good Summoner will be far behind a good Black Mage. Although Black Mages is greatly dependend on RNG sometimes. The base damage for a BLM is good, but if you want to get really high, it's more a factor of luck instead of skill.
You have a raise will can be handy will will destroy your DPS. You do have Eye for en Eye and Enhanced Virus. Pretty sweet, but pretty much useless.
DPS should focus on DPS and not pretty utility that isn't really imperative. If you want an imperative skill, try Dragon Kick on T13