I would rather increase difficulty so healers are required instead of making them pure DPS with healing abilities. Right now you only heal group wide AoEs and tank busters. Anything more is generally dps being vuln sponges.
Ideally I think WHM would be pure healer with few attacks, holy aoe stun, aerora aoe dot, and maybe stone with a chance to proc cure2 or stoneskin if they're feeling spicy.
SCH would primary have dots so they can focus on micromanaging their fairy and positioning shields.
AST would have more aoe star explosions so they could focus on an expanded pokemon deck instead of match the colors. (Buff other dps instead of directly doing it)
SGE would pull out a gun and have the real dps combo system that heals.
Thats my ideal setup. More about choose your own playstyle rather than everyone has to max deeps or die.