But they did.
Cure II always had a cast time of only 2 seconds.
Medica was 2.5s, now 2s.
Medica II was 3s, now 2s.
Holy is an outlier, they reduced the cast time from 3s to 2.5s. But the AoE stun is also an outlier and a tradeoff I am willing to take.
Except Holy and Raise all the cast times of WHM are shorter than the actual GCD.