Best thing about Astro heals for me is the short cast time too. Even if I'm not using the time between GCD for cards, it's very nice to just have all my heals with cast times of 1.5 to 2s at most.

I too prioritize Crit > DH > Det > SS >>> Piety for all my healers, although in my case that's doubly reinforced by being primarily a Scholar healer which doubles down on the crit priority. It's super handy that all healers/casters do well with that priority, since I never have to think about which stats I'm focusing on and don't have to worry about multiple gear sets.