The problem with making GEO a healer is that, no matter how mechanically unique and different you make it from CNJ and WHM, every single player that doesn't already know how different it is will immediately wonder why there are two healers that do the same thing.

This means every new player that sees the job's thematic design, and every current player that doesn't pay attention to patch notes, watch videos on new classes, or play healer enough to understand the subtle differences between healing jobs, will look at GEO as WHM 2.0. That is not a healthy way to design a class.

This is why there's a growing momentum of people looking at GEO to be a caster tank, probably using barriers and the elements to protect themselves from damage.