I think your problem is more of a feel thing than an actual effectiveness issue.
all the hype about astrologian was around the cards and stances and both of those are about the most disappointing aspects of the class.
honestly you could probably ignore cards completely and your raid might not even notice anything different while stances are pretty much just opposite your healing partner and done
while the whole story for them is just reinforcing "OMG cards!" like every single quest
the rest of the astro kit is pretty solid though.
It may not have the damage reduction potential of a scholar or the bulk healing of a white mage but it kind of still fits in
