Targetting on a controller does sound like a pain, but rather than change the Job to suit the controller's targetting method, I think it'd make more sense to just make a better controller targetting method. For example, if you could hold the button to play the card, and it brought up an 8-way selector thingy (think Monster Hunter Radial Menu). Select your target for the card with RightStick, and let go of the held Play Card button to play that card to that target directly, without having to ever unselect the boss

The best part is, such a system could be expanded from just cards to other moves. Esuna, Essential Dignity, Exaltation/Celestial Intersection, Synastry, stuff on other jobs like Fey Union/Lustrate/Excogitation, Afflatus Solace/Benediction/Tetragrammaton. Even on non-healer jobs, like how many times have you seen complaints about how annoying it is as a DRG to target an ally for Dragon Sight, or how people use a Macro to auto-target an ally with it? Or how about those tank shareables, like the 25s CDs (TBN/Nascent/Heart of Whatever), or Aurora in particular on GNB. This would help with that too!