"Bring the player, not the class" is the best way to answer this question, yeah. A player who knows their job and the fights will always be a boon to the party, regardless of what job they're playing.

That said, "Wet noodle" isn't really a good way to describe NIN pDPS. They got some really good burst damage and while they're not as strong as a SAM or MNK, they can hold their own really well on top of boosting the entire party's DPS output. Many times I see myself as a NIN topping the DPS charts in a party full of MNKs, SAMs or BLMs simply because I know how to optimize my job; put enough effort into it and you can pull off some good damage regardless of what job you choose in the end!