The vast majority of our power is in our ability to hit things with our sword and survive the trip doing so involves. Blood options that help doing that are going to be far more valuable than ones that have to make some awkward workaround that leaves them viable in all three forms. There's things the Domain of blood does well, and provide the most value per pick/arete, then there's things it can do but it's going to do less efficiently. The sort of direct buffing quickening is giving us is pretty clearly skimming off the cream of the ability as suited to us. Waiting until we get some sort of enhanced debuffing ability that's always viable is going to cost more for what if offers overall, all the while burning away time we could have been benefiting from the multiplier boost to advancement. Take the low hanging fruit, it tastes good.