Question: What is Dragoon best at ?

[rickyguo]

A well played Dragoon is much more mobile than its punchy melee dps counterpart, thanks to all its jumps.

Our jumps have a cd of 90, 180 and 180. I think shoulder tackle has a cd of 30.

It's also a DPS bonus for the DRG, if a DRG can buff another class and has the same kind of DPS as a MNK who in their right mind would take a MNK then?
About Mantra... I do use it sometimes just because I have it but there isn't a single situation in the game where I think Manta is really a big help, so I don't see whats the deal with Mantra. o_o
The whole content can be cleared just as easy without it since the heals are really huge in this game.

Going by that logic, if monk+bard dps is higher than drg+bard dps even with the disembowel buff, which it actually is, is there any reason to take a drg to a fight without 2 bards?

Mantra helps on big group damage and for creating a bigger succor shield if you're not nearly as geared to mitigate aoe damage such as megaflare. It might not be necessary but it still helps, and besides, even mages ballad isn't necessary for all the content if your healers don't overheal.