DRGs are certainly not that far behind monks but it's true that if you want dps, there's no reason to bring a drg over a monk unless you have 2 bards.

Total sustained of a drg+bard is less than that of a monk+bard seeing as a monk will have around 8% more damage and disembowel doesn't work on dots.

The only time total raid damage will increase if you bring a drg is if you have 2 bards.

DRGs are also probably the most squishy dps class, while I think we get more hp from our job crystal, we take ridiculously more damage from unavoidable magic aoes.

I think DRGs are pretty balanced as a class if we compare to any class but monks.