Using tadpoles should be an oath violation at least for Devotion and Ancients, given their tenets. I'd also imagine most gods would disown a cleric indulging in something connected to beings which are practically universally hated.
The main problem with the powers is that they aren't needed, plain and simple. No fight in the game, Tactician or not, is difficult enough to warrant relying on them as a tool. Having a mandatory illithid with you for the final stretch showcases how stupidly busted they are by turning the final battle into an utter cakewalk in a game that already stopped being challenging for the past 20 hours or so, resulting in a very anti-climactic resolution - and the game's plot's rotting away at the seams as of Act 3 as-is.
