I personally like WHM having access to stone, aero, and water (it's shown in one of the alpha videos). Removing them would ruin the lore for CNJ. I find the powers of creation for WHM and powers of destruction for BLM are more interesting than WHM just being the power of light. WHMs have had some of these elements in a few of the previous games anyway. What I personally think should be done is make thunder, fire, and blizzard more useful (as you said) and give BLM access to stone, aero, and water as cross-class skills (assuming this system is still there) and also give them the ancient magic versions of all the elements.