Beside using it on Plundge for aggro or abyssal drain for some sweet heal, the problem is that for the vast majority of skill it's a simply potency increase.
I think people just want more nuance.
The spam in itself it's a matter of preference, I don't mind it, some people do, but to me the core of the issue is the lack of impact DA has.
This, on top of having a single dps combo, makes the job very simplistic (altough one could argue that doing a different combo once every30sec isn't super engaging too)
But for instance, let say they'd cut in half the MP gain from Syphon Strike (to reduce the amount of DA you could do) and they'd add new effect to DA on top of the 140 potency
For instance
Soul Eater: Double healing received from Soul Eater
Carve and Spit (no DA) : gants 2400mp 160potency
Carve and Spit DA : Heal for 20% of missing health 300 potency
Blood Spiller: consumes an additional 2400 to inflict bleed: Potency 70 duration :12s (280 potency for 2DA worth of mana basically)
Salted Earth (DA) : Salted Earth damage heals you for 50% of the damage done. (no potency gain)
Unleash (DA) : Increase damage to 150potency per target. No longer increase threat generated (didn't really think about the math here, the idea is just to make it a good AoE for damage and not aggro only)
With less mana, each DA would matter more thus making the choice more relevant as long as the effect is more than more potency.
100% more healing on Soul Eater is significative over the course of a fight.
A well executed carve and spit would be seen
I didn't think about what I suggested for an extensive period of time nor are these suggestion meant to be balanced within 4.x serie , but the point I'm trying to make is that DA could be more than simply +140 potency
It could be something that you pop to make a difference and enhance a specific skill for a specific situation (a bit like Abyssal Drain, when there are a lot of ennemies on you, the heal can be a life saver, it is nice, and there could be more nice skills like this.)