Diamondback and whitewind arnt even that bad in a raid setting actually.
White Wind: with the exception of snapshotting high health, the only time you would want a dps to sacrifice a gcd to help out the healers is during a heal check, and during a heal check, your health is low, if your health is low white wind sucks. Sure you could do bene + whitewind combo, but in what world is that better than the plethora of high power dps neutral healing options healers have. It doesnt even help in solo heal attempts, as the limiting factor for solo heal is mechanic targetting not healing throughput.
DB: this ability is a trap, there is not a way to make this a valuable skill on a dps which wouldnt make it just way more clunky than just having the off tank do it. Any situation where diamondback would be useful to have on a dps would be a situation where somethings gone terribly wrong or a gimmick run. Even on bosses that target 1st and second aggro having to DB will bleed so much damage to keep the blu alive that you should just have an off tank.
Edit: on the topic of dungeons im in 2 minds, on one hand yeah chain cc would be powerful in dungeons. On the other hand dungeons are broken content by design and can be literally solod by warriors/ paladins, and already optimally run with 3 dps and one tank, so its impact would be minor.