DNC was broken because they cold give "JA" Category Haste to other jobs, and only 2 other jobs in the game have JA Haste, and only 1 job can cap it, and that's temporary.
Since Haste from gear caps at ~25%, haste from spells caps at ~43%, and the new haste cap is 80%, this means that even with SV Marches, Haste, and 25% in gear, all DD not using Hasso or DB can receive the full benefit of Haste Samba and those using Hasso can actually hit the cap for more than 30 seconds.
This is huge for every melee in the game when receiving Haste+Marches becase of the nature of haste. Find a strong haste built DRK/SAM (Apocalypse needed), SAM/DRG (Wyvern earring needed), or MNK/Anything (BB needed) and give them a RDM, BRD, and COR and they can literally self SC by just tping, no Meditate, no Jumps, no Absorb-TP, they just swing that damn fast.
Then there's also the defense down step, which stacks with Angon and Dia III.
DNCs are extremely powerful support already, it's just most people are too HELP I AM TRAPPED IN 2006 PLEASE SEND A TIME MACHINE to notice. Now they're like raptor jesus with laser arrows and holy water for all.