Isn't this like saying MNK is getting progressively unnecessary? You could argue that even though it's the highest individual DPS, that extra DPS is unnecessary because MNK has no raid utility. So a DRG could do 90% the DPS of a MNK, but also increase everyone else's DPS with Battle Litany+Disembowel, which pushes the added damage past what the 10% deficit is compared to MNK.

In that regard, WHM has potent heals and HoTs that could allow WHM additional time to throw out Stone III's/Aero's/Asylums. Doesn't WHM have the best single target DPS amongst healers? Couldn't that be their 'raid utility' in a sense?