DPS curing walts potency does not equate to healer Cure III potency.
ilvl 470 300 potency curing waltz heals for about 7.5k (non crit) so thats 15k stacked (600 potency).
ilvl 451 550 potency cure III does about 19k (non crit).
So even with a ilvl difference of almost 20 the dancers 600 potency curing walts healed for 4k less than the white mage's 550 potency cure III.

Meanwhile I think curing waltz has it uses obviously, just pointing out that the point you made about it being higher than Cure III doesnt really mean anything given that our scaling is entirely different.