In my estimation, about 10%-15% of a damage-dealing card's damage output comes from rolls, with the rest from activation of special abilities (assuming no overkill, etc.). Even if it were not taking the place of a useful special ability, is there anyone who would stop auto-spin in order to achieve "Over the course of three turns, increase damage by 5-7%"? This assumes a 50% increase in the probability of matching symbols, which is probably generous. Or worse, would you enter a zone where you had to rely on a 15% (rather than 10%) chance of being healed? Even with the presumed counterpoint, Horsemen, increasing the odds to 25% *per symbol* (a ridiculous assumption) would not double the damage output from spins.
When I first started coming to this site, I remember reading "Light Healer > Water Healer because the healing occurs without cluttering the reels." To which one might add, "but that's OK because it doesn't actually clutter the reels." I presume this is an attempt at translating "all hearts become rubies" from match-3 games. However, since the entire point is knowing when it's favorable to activate, it's confusing why one would even attempt the analog.
Given this, every newly released card has an active/passive combination in which one is situational and the other completely useless. Cards like the dark version of holy priestess are interesting, good for arena, and I could foresee situations in the future where I might use them (even though I never have to date). Cards like Ceto are just garbage unless the active is completely reworked.
P.S. Great game, the rest of it is fantastic. I only mention this because it sticks out like a sore thumb in comparison.