For SCH I don't mind how it currently is, as the shields (and excog.) allow you to be pro-active, while Aetherflow abilities allow you to be instantly re-active; so DPSing in-between feels natural.
For WHM I would actually like to see the return of ARR/HW Cleric Stance, as, to me, it made DPSing as a WHM interesting. (Also, SB WHM just feels a bit watered down, and its potential healing now spread over just a few too many abilities / procs / lilies; bringing Cleric Stance back would let WHM be simple and powerful again, without being OP).
For AST, I'm not sure, I enjoyed levelling it, but at 70, with heals, cards, and DPS it just feels a bit messy (and again, watered down for the sake of being 'diverse')... so yeah, maybe buff cards (e.g. lower re-draw cooldown) so AST can spend more time buffing others DPS and less time spamming it themselves.